Cubase Studio 5 Importing midi files

I havent used Cubase Studio 5 for over 12 months. Previously I had the program running and was able to import midi files. Today i cannot. i have tried the import function but the files will just not import. i have tried to update my cubase but as per my previous posting in this forum I am also unable to do that. i am frightened to reintall Cubase as I dont know where to look for my serial number?

If your license is present on an e-licenser (soft or USB, I don’t know which Studio 5 uses) you don’t need your serial number to reinstall.

You may want to try trashing your prefs before that.
https://www.steinberg.net/forum/viewtopic.php?f=19&t=22557