Hi, let me help you.
What size is the drive, and does it show up in File Explorer normally?
The usual reasons a drive doesn’t show up in the list are that it’s smaller than the tool needs (at least 16 GB is the safe minimum, and more if you tick “Back up system files”), that the drive is partitioned oddly or shows up as a removable disk with a weird partition style, or that Windows sees it as a fixed or flagged device. A leftover partition table from earlier use is the most common culprit.
The quickest fix is to wipe it cleanly. Open Command Prompt as administrator, run diskpart, then list disk, select your USB disk by its number (double-check the size so you don’t pick the wrong drive), and run clean, then create partition primary, then format fs=fat32 quick, then assign. Anything on the drive will be erased, so back it up first. After that, unplug it, plug it back in, and reopen the Recovery Media Creator. It should appear in the list.
If it still doesn’t show, try a different USB port (ideally a rear port on a desktop, not a hub), and if you can, a different drive.