First thing: the events are still there if you look at the calendar on the web? If not then there is nothing you can do (possibly in this case they weren't actually synced).
Assuming they are, are they different from the others that did restore, e.g. in a different calendar, a different category of some sort? Especially if they are in a different calendar, check the settings of the calendar app on your phone to make sure that it thinks it should display them. It's possible that they've been synced but the calendar app just thinks you don't want to display this particular calendar.
If they are just in the same calendar as your other events and there is nothing visibly different about them, you could try exporting them to .ics files, then either re-importing them or copying those files to your phone and importing them directly.
In the last resort, you re-type them manually into the phone.
Without more information that's the best I can do.