How do you come up with ideas? Like where do you go for inspiration for things given how annoying writers block can be?
I'd want to separate these out a bit, since they don't seem to me to be the same issue.
First (and simplest): I kinda hate using the term "writers' block", as it tends to mean too many different things to too many people, and it's too easy to be misunderstood. The term gets used for everything from being unable to start writing, to being unable to keep writing, to being unable to finish writing.
When I use it (and of course your mileage may vary), it means "hitting some spot in the writing—usually in the middle, hardly ever in any of the other places—from which you're having trouble moving forward."
After many years' practice, this usually means that I've run into a place in the narrative where the primary character involved in that section has issues going on that haven't been resolved: unanswered questions, uncertainties about what's going to happen next. (And let's be clear, as one writer to another: the uncertainties are yours, not theirs. The character is waiting for you to achieve clarity. You get clear? They get clear.)
When I hit this kind of problem, I set aside time to examine all the main characters' situations and see whether everyone knows where they're headed, or at least what they're headed toward. Normally I find that some one character has questions that haven't been answered, or some necessary conversation (with another character, or fate, or God, or you) that hasn't yet happened. Or hasn't happened to their satisfaction.
I've dealt with this problem in about twenty different ways over four decades, from the cold-blooded-analysis method of taking apart previous chapters or sections of a work, looking at the final end-state chapters or sections, and figuring out what's missing... to the Sherlock-Holmes-in-his-sitting-room method of making your character sit down in the Empty Chair and tell you what their problem is. (Which is also a mode favored by psychiatric professionals the world over, these days. Believe me, I did not give an entire novel that title accidentally.)
So: as far as I can tell, "writer's block" is almost always code for "a missing transaction (or desired transaction) in the narrative that you haven't yet identified and resolved." See above. Or that transaction may be some sort of failed communication between the outer, author-to-real-world world, and the inner, character-in-created-world world. Track it down and resolve it, and everything will be good.
Meanwhile, as for inspiration and finding ideas:
This is... not one of my problems, so I'm probably the wrong person to be asking. ...Going anywhere for inspiration? Why would I do that? It hunts me down in the street. It grabs me from behind when I'm trying to deal with the email. It gets me in a hammerlock when I'm watching somebody else's TV show.
In short: gods help me, I've been a Having An Idea person since before I started to read. I'm the one who, after being read a sleepy-time fairy tale about a prince rescuing a princess, looked at her mom and said, "Why can't it be a prince rescuing a prince?" And you see where that got me: half a million words, and (as we say on AO3) These Two Idiots. (Or: "What if magic came with a user's manual?" ...Oh gods.)
At this end of time, it would be tough for me not to have an idea or three for a novel before I've had my tea.
(a) Wake up. Reach for iPad.
(b) Read news. Ugh. Naughty, naughty world. (With occasional bright spots.)
(c) ...And then wonder: "How would it be if X [thing that you just read on the news] happened in Y [entirely different universe where conditions (z) pertain]?"
(d) [make up entirely different set of conditions that don't pertain in local or even non-local reality]
...The good thing about this, of course, is that I know that ideas are cheap. Ideas are nothing. They're a dime a dozen. A dime for two or three dozen. In this regard, they observe Sturgeon's Law. (Gods rest his gentle soul.)
And more to the point: ideas are easy. It's execution (especially good, deep-delved, worthwhile execution, over tens or hundreds of thousands of words) that's hard.
Which, ninety-eight times out of a hundred, leads to:
(d) Examine idea, put it in the Scales of How Hot You Are For It, watch how the Scales weigh it and find it wanting: then throw idea out, get the hell up and have some tea.
Or, in those two other cases (twice a year, maybe); when an idea comes along that pulls the Scales down and is heavier than the Feather of Your Current Intent in the other side of the Balance—something that has some weight to it, some bite, one that resists being thrown the hell out:
(d1) Get up, have tea, write a premise filling out the idea to at least a couple of pages' length... and then start working out who the hell to market it to.
...Now this is my personal modus operandi, and I've been enacting it across various media for somewhere between fifty and sixty years and change, and there's no way I'm going to stop now. But I submit to you that it might be possible to train yourself into being this kind of What If? person, by simply spending—oh, a week, even two—asking yourself "What if...?" about everything. Every single thing you see, hear, or come in contact with. Why must this thing/this situation/this world be the way it is? Why can't it be some other way? (And then you start reasoning it out. What other way?...)
Frankly, there's no reason this shouldn't work. In fact, considering the ridiculous malleability of the human mind (and I speak with my psychiatric-nurse hat on, here) it's very likely it would work.
There's only one problem with this concept. I have no idea what to tell you if it works and you then decide you want to turn it off.
Because once you've started training your brain into this mode of questioning everything, looking under all the rocks of so-called Reality for the previously impossible impossibilities... there's no guarantee you'll ever be able to make it stop.
It's heaven for me, no mistake. But for you?
Be careful what you ask for. You might get it.
Anyway: hope this helps! :)