My USB Memory stick wont show on My Com...

There is normally one of two things that goes wrong with a memory stick.

Either the usb connector's soldering onto the board fails or the flash memory itself fails.

If the flash memory itself has failed you will not be able to repair it , but if the usb connector came loose, it will cost about $5 at any repair shop to correct if they don't do it for free.

You can also open the casing up and solder it yourself as the soldering is normally quite big.

Kind Regards
Stephan

I'd try in different USB ports and even maybe on another computer first. If still not working, contact the manufacturer. If you truly mean 'Memory Stick', as in Sony's, you can find support options for repair or replacement. Alternately, you could attempt to go through a data recover specialist.