How to reset Mac App Store (to factory defaults)?
You can delete appstore cache files : ~/Library/Caches/com.apple.appstore
This may not solve the entire issue you should look in your /private/var/folders and delete the com.apple.appstore forlder for me it's in /private/var/folders/08/366wf94902jf_hy69t1d_92r0000gn/C/com.apple.appstore It's gonna be different for you .