I have a worst problem in my phone..The thing is that I can't download any app anymore!!!!except for app cache cleaner but the second thing is even if how many times I deleted the cache in all my apps or deleted some files in the file manager!!!IT DIDN'T WORK!!!!!!!!! PLEASE HELP ME!!
It sounds like there is to much on the phone. It also could be how much is running (the apps) in the background, which adds to the space usage.
You may want to move your photos, videos, music, etc., to a computer or cloud account. Which is a good place to keep copies of these things anyway, as then you won't lose them if you lose the phone or it breaks down.
Then you can clear out (remove/uninstall) the apps you don't use. Then I would download a program like say "Clean Master" or a similar program. Use this to clear up more. Then do all these on the card as well (not just the phone). Once you have cleared it out and cleaned it up. You may also want to clean up any things the apps have accumulated on the phone and anything the browser has as well.
Then restart the phone.
Now you can copy back to the SD card what you want to keep on it. If you do this from the computer via a USB cord, then it will be simpler and the computer can easily tell you if you run out of room and what files are the cause.