It sounds like your initial install of mssql server was done to the I drive. I hope you didn't wipe it out... fixing it can be difficult. Here are few things to try...
1) If you don't have an I drive anymore, create one temporarily using subst:
subst i: c:\some-path-you-like
& try and start the server. Once you can get the server started, you can re-map the tempdb to a different directory by doing this:
Alter database tempdb modify file (name = tempdev, filename = 'C:\Sqldata\tempdb.mdf')
Alter database tempdb modify file (name = templog, filename = 'C:\Sqldata\templog.ldf')
After this, you should be good-to-go. You can then remove the subst'd drive by doing this:
subst i: /D
It's also possible that your master database & log and error log are still on the I drive as well, and those can also be moved... but a little differently. You'll need to modify the mssql service startup-parameters to include 3 additional options:
-d is the fully qualified path for the master database data file.
-e is the fully qualified path for the error log file.
-l is the fully qualified path for the master database log`
i.e. -l c:\wherever\mastlog.ldf etc...