Please SO much help,my mp3/4 i want to delete some files

Before few days i bought mp3/mp4.at first it was hard to conect it with the computer but it was possible.now it doesnt want!!! sometimes it shows ''usb device not recognized'' but sometimes.
The second problem is that i NEED to delete some files from the mp3 but it can’t unless its conected with the computer!!! ;;;( i searched hard in the net abut the not recognising buut it dont help ;;;(
Is there other way to delete the files from the mp3???
Please so much help me!!!!!

i need urgent!
yesterday i was in a hurry and i dowlnoad some files and i put them in the mp3 so i’ll see them late,and when i opened there was smtng nudity!!!! ;;;;;;( now i can’t take the mp3 to the shop so they see the poblem with recognizing also my mothe is going to see my player
why this hapens to mee??!! ;;;;(