Thanx for the replies.
I have cleaned the USB port with alchohol and canned air - no change.
I tried Air Kies and Airdroid, and it dosen't work. The browsers can't find the phone, even though the phone can find and use the network. I changes the settings in Windows according to the documentation for the apps, and still it doesn't work.
I backed up the important stuff to Google drive.
Can I upgrade my OS with out the USB connectivitiy?