samsung s4 phone storage issue

[pukmuna]

hello i have a samsung s4 gti9500 which has a 13 gb phone storage
when i connect it to my desktop using a USB it shows only 1.93gb of phone storage
WTF!!!!!!!
please help me guys
help me fix this problem

 

[Scott Kenyon]

It's showing 13 free in settings on the phone?

 

[pukmuna]

yes but in the desktop only 1.93gb

 

[pukmuna]

and now when i access my 4n using webdroid it says that i have 893mb of internal stoarage space
WTF i think its must be a virus in my 4n