There's currently no reported issue with Uplay PC login. Could you try the following?
- Uplay passwords are 16 characters long max. but the password field lets you type in more (will be fixed in the next update). If you have a long password, make sure you only type in the first 16 characters.
- If you have tried to reset your password during the downtime on Sunday the 15th, some members have reported they were able to login to Uplay with their original password instead of the new one.
If this doesn't work please contact Support at
http://support.ubi.com.