I updated my iphone and lost all my contacts what am I supposed to do?

The iphone is designed to be synced to your computer regularly.

Your contacts should be in whatever program you have chosen to sync with.

If you have failed to sync your contacts, then they are very likely gone.

You can try restoring from backup.

I was asked about ICloud when updating. Would that have been what it synced to?

I had this problem post 6.1. Not sure if it was a coincidence, but I'd just recently changed my password after being convinced I'd been hacked, due to being told I was entering my password wrongly, repeatedly by iCloud / iTunes. It turns out my iCloud account on my Settings -> Mail, Contacts and Calendars was listed as Inactive. Putting in my details, turning off Contacts over iCloud (thus deleting them) and turning them back on again, repopulated my contacts from iCloud with numbers attached to them.