Good day to you!
It’s a widespread problem; in most cases, it is common for conventional car stereos, made in 2015 and earlier. Old mp3 players in these stereos cannot read flash drives, formatted in NTFS file system. If you’ve bought a new flash drive, most probably, the system it has been formatted in is NTFS. Modern Windows versions also on default offer to format flash drives in NTFS.
What to do? Everything is quite simple! You should format the flash drive in FAT32 file system and you’ll have no problems with reading it in your car stereo!
If the size of your flash drive is less than 8 gigabytes, you can follow our instructions to format it (link), the only difference – you should select FAT32 file system:

If you have a flash drive of a larger size – the standard formatting program in Windows won’t even offer you to select FAT32 filing system, and you will have to use a special program, which we will discuss further.
A car stereo fails to read a flash drive:
1. Download a special program GUIFORMAT32 (Download from the HelpDesk.zone server | the author’s site). It’s a simple program that contains no viruses or malicious software and requires no installation. Before downloading it to Voprosoff.net server, I’ve checked it for viruses.
2. Start the downloaded program; you will see this window:

3. Select your flash drive out of the given devices (you can find its letter in “My Computer” section), type in the name you like (you can skip this step) and click “Start”. That’s all!
Now you can record your favorite music on this flash drive, and your car stereo will easily read it!
Good luck to you! If you have left any questions – don’t hesitate to ask!