USB will not transfer to phone irregardless of file. ( unsure if phone issue or computer. )

[Android Central Question]

My USB cable/phone will normally accept files no problem. Today I encounter the most infuriating issue. As always because half of the time the internet likes to kick my phone out, I end up resorting to downloading APK of specific game files. It runs and applies them to the phone perfectly as long as there's enough space for the file. The problem being it won't transfer ANYTHING. Not files, nor pictures. Size doesn't matter, it has at least 1+ GB free. The computer gives a message consisting "the file cannot be found." Which is bull because the computer itself loads the file just fine ( specifically the pictures, they're not deleted or anything ). The computer itself is newer compared to how long I've had the phone and would formerly accept files without an issue unless there's not enough space. I tried switching cords, no change, I restarted the phone, nothing. Debugging is on and ascertained it's the option "MTP" being on. Nothing.

 

[WolfLover456]

I love how no one's helping me on this.. -_-

 

[ManiacJoe]

Which phone?
Which version of android?
Which carrier?

Mac or Windows? Which version?