Unreal engine stopped working after compile a blueprint

Need help:
I was setting up a double tapping function for the character’s movement, I found the instruction online. After I set up the bp, I clicked compile, then Unreal engine stopped working, and I couldn’t run it anymore, it stopped working every time I try to open it, even after I restart my computer. Is there anyway to fix it?
Sorry for my bad English.
My level version is 4.8