All my psd files turn to pdf icons

I recently had a problem where all my psd files from my folder have the pdf icon on them, once I try to open them it says the file might have been corrupt or something like that, 

the only solution is going to photoshop clicking open and clicking on the pdf icon/psd file there and it opens. 

if anyone knows a solution to this, that would be great otherwise I will upload an image of the problem, since I'm not near my computer now. 

Thanks!