What the phone 'says' it has on the specs is not what you have access to. That is the complete storage, which is partially taken up by the OS, preinstalled apps, etc. Then every app you put on the phone, and all the data each of those apps creates (like say Facebook) add more and more things to the phone. Taking up more space. Then you have any pictures you take, etc. It adds up. Quickly actually.
Yes it says misc folder have taken up 53gb however when I open the folder I have 5 other files named utsystemconfig - 24kb,.data storage 12kb,thumbnails - 8kb,recording - 8kb lastly my audio files - 4.41gb thats all
It is possible that the system has files in there that you can't see, or there is something on the device that is taking up storage that you don't want on it. Have you tried checking the device for viruses and malware?
In the end, you may want to back up your personal files and contacts to a google account or a computer and then "Hard Reset" the device. You will have to reinstall apps after, but this will wipe any/all stuff off of it and start it over fresh.