Why am I suddenly getting a "compile error" on Writelatex and how do I stop it?

I started writing a lab report using Writelatex and it was working fine for a few weeks and I added images etc.

Then one day I tried adding a new image and got a "compile error" and couldn't insert the image, and I tried inserting the images I had already inserted into the new part and they wouldn't work either.

I could write text and it would appear in the template.

Now I just logged onto writelatex and my template isn't showing up on the right and it still says "compile error".

Why is there this compile error and how can I get rid of it?

I'm on mac if that helps.