Weird Files and Folders

[#1]

I recently bought an 8GB mp4 player, to replace one that I lost.... almost the same as the one I lost... has the same "desktop" and welcome screen.... the file system looks the same... although the buttons look to have been updated ....
I only want it to play MP4 Music videos... and have successfully  transferred some over to it..... and they play o.k.  however.. I decided that I would try to make them all the same (similar) volume level and used MP3GAIN..... this, was a mistake........ !   although the videos play, and the music is ok.... the video has become all "blocky"... and totally spoilt.. so..
easy peasy... erase them and re-install them...
normally this works quite well.... however... ( again) ... instead of leaving the folder "empty"... it now has quite a lot of folders (none were there in the first place) with unintelligible names... consissting of symbols and numbers and the odd letter, and some chinese type symbols too !... there are a lot of single files listed too.....
Now... you say.. ok...erase them..or delete them... nope !... not gonna happen.... get a message saying the file name is too long.... also... on checking the "properties" of the parent folder it shows.....

189GB (203,262,966,518 bytes)     which is not quite true, considering the whole item is only 8GB ! ! ..
102 files
78 folders  
On investigating the whole MP4 player it says the files have disappeared, ( by showing less content than before ).. and that the total content is ..
2,91 GB USED
3.93 GB FREE SPACE
capacity 6.84GB  
I have tried to rename files before erasing or deleting them, but this again. reports the file is too long .!...  The Parent Folder of the offending folders and files, did rename successfully, but trying to erase or delete that, also returns the file too long message...

any suggestions?

EDIT EDIT EDIT......

Just found that these folders have a date of 24 DECEMBER  2068 .. some have 19 July 22043 and some have 14 Oct 2052  some of the files have 1st FEB 1992  even got some dated 14 july 2100...
none of them have the Date Modified, as yesterday`s date !...

Yes, I did do a scan with Avira on the files and folders...... no threat found ! ! ...

[#2]

Many devices have an option to reset to the factory (as new) state.  Maybe you can do that and wipe the slate clean?

[#3]

It sounds like the file system has got corrupted.
You'd be best off doing a reset as above or a drive format.

[#4]

Thanks, Guys.... after some "fiddling about"... ( manual is in CHINGLISH ! ! )... and doesn`t actually mention resetting.....
Found an "advanced" section under the settings.... one was "format the internal memory".... which I did... and the other was " Check the system".... which I did... it then did an auto Re-boot... and ALL my music files and the offending ones have disappeared....
so I can now start again.... 
Much appreciate your helpful advice....