Are you possibly logged in under a limited account ? If so, log in with an account that has administrator access.
See the paragraph below.
To reset your restore points, please note that you will need to log into your computer with an account which has full administrator access. You will know if the account has administrator access because you will be able to see the System Restore tab. If the tab is missing, you are logged in under a limited account.
After logging in as Administrator, did you try these instructions ?
1. Turn off System Restore.
On the Desktop, right-click My Computer.
Click Properties.
Click the System Restore tab.
Check Turn off System Restore.
Click Apply, and then click OK.
2. Reboot.
3. Turn ON System Restore.
On the Desktop, right-click My Computer.
Click Properties.
Click the System Restore tab.
UN-Check *Turn off System Restore*.
Click Apply, and then click OK.
I'm wondering if you are logged in under an Administrators Account.
Go to Start>Settings>Control Panel. Click on "Users Accounts".
If your Logon name does not say "computer administrator", then you cannot make the necessary changes and the account must be changed to Administrator.
Is there another Administrator listed ? If so, have them log in and see if they have access to System Restore.
If that is the case, then you may have to remove your Administrator account and set up a new Administrator account for yourself.
This is to replace the System Restore tab, if it is missing and for nothing else.
I researched this and found the following. This seems to be the least troublesome method for restoring that missing SR tab. Please, use caution and backup as advised in the link, before attempting this registry edit.