Pendrive unaccessable

After having removed a pendrive detected by USB controllers as Philips
MassStorage Disk USB Device without the typical precautions (the USB
was trying to autoplay in a portable pc), I face the following problem:

- In the same portable (WinXP) where the error occured (now that pc is
gone because not mine), once the USB is inserted I saw that the pc
tries to autoplay with a single mp3 which is inside the USB pendrive,
but without success (probably it was the same mp3 that was loading when
I removed the Pen).

- In all the other pcs I can see that it is assigned a letter to the
Pen and the USB controller detects it correctly. Yet in explorer I can
see the icon, but I cannot see any size of the of the drive (256MB the
actual size) and I see in properties "used space" "free space" with 0
bytes.

- Software recovery (Norton Doctor, PendDrive data recovery,
FileRecovery Pro, and some others) cannot see the drive. Sometimes I
have the warning: Please insert the media, if I try to load in the
program the drive letter.

Any idea to recovery (or even format: now the command does not proceed)
the USB drive?
Thanks in advance
A.R.