I'm unable to get my playercontroller to respond to movement inputs anymore (It used to work perfectly fine until today)

Basically, I’m very new to the Unreal Engine and I’m working on something involving it for my school personal project. 
I managed to get my player character and game-mode to work perfectly fine since the start of the project, however today it suddenly stopped working for me - it was working this morning but stopped working after I built my level more. The mouse inputs still work and I can move my camera around freely, however my movement keys have suddenly gone non responsive and I am unable to resolve it. 
Any help is appreciated

If you didn’t change any logic and only added more meshes to the level, then maybe one of the newly added meshes blocks your character with its collider? Here is what you can try to narrow down the issue:

Add PrintString nodes that print something to your movement input events and see if it prints anything after trying to move. If it prints it, then it means that the events are fired properly, but something in the scene prevents your character from moving.

… If that’s the case, go through your newly added actors and disable collision on them, then try again. You can even go to a 100% problem-killer mode: Make a copy of your level and keep removing actors until your character will move again.
This way you can find the thing that ‘corrupted’ your scene and fix its collision or remove it.

Ahh thank you Slavq so much for your reply. I’ve finally figured out that the problem was a rouge static mesh I added with a bizarrely large collision size. Even though I had checked the player collision view, I couldn’t see it whatsoever as it was extremely large and I was always within it. I tested deleting parts of my scene in large scale batches, and found out I was able to move. I was eventually able to narrow it down and fix the problem by modifying its collision.
I’m extremely grateful for your help. Thanks again!