Rockstar usually remove songs from their games for their 10th anniversary and imo the new ones aren't that good. Perhaps you accidentally updated your game and you want them back? Well you are about to learn how :)!

First of all download the original soundtrack
IV: https://mega.nz/#!neR1lRSB!kksFUF8CJItq8osFNACo4ppRFkxBEP9ItLqulqFSu_8
Alternative links if this one doesn't work:
https://www.dropbox.com/s/htvhj8y9mlmff51/IVRadios.7z?dl=0
https:// www.mediafire. com/file/y9yeeaas32r62mz/IVRadios.7z (remove the spaces, steam doesn't like mediafire)

EFLC: https://mega.nz/#!afQ0QQSB!PWX_P5Lnha_8Fnc1l8HZEFk2LhZQlo9xjPGAyF_Jcu0
Alternative links if this one doesn't work:
https://www.dropbox.com/s/789f29t80qp8sis/EFLCRadios.7z?dl=0
http:// www.mediafire. com/file/yt7ds1sb22q3r99/EFLCRadios.7z (remove the spaces, steam doesn't like mediafire)

Now unpack the archive and you will have a folder called IV/EFLC (depending on which one you downloaded), open that folder and copy its content, paste it into your GTA IV/EFLC folder and replace any file you are prompted to. That's pretty much it. I have also written this in the ReadMe file.

Enjoy!

Also later on I found out that it was already made with a downgrader however I still think this is much more simple and easier. Thanks for taking your time.

If you do have any issues, feel free to add me on Steam and I will try to help you! Have a nice day!