how to fix tomtom go?

my tomtom go v2 is no longer recognised by my pc or lap top. tried the reset button tried different usb leads and ports. It just came back from repair centre for charging fault repair, he added map upgrades etc and the voices i added some time ago were gone as well as the low bridge warnings. I wanted to put these back on so deleted 2 of the repairers adverts he put on the sd card, now it is no longer seen by my pc. can any one help