The fixer may have overwritten your legitimate version with a fake or one already in use and you may be able to change that if you have the original Product Key printed on the case. If you have, press your Windows key and R together and into the Open box, type regedit then press Enter. From the File menu, choose Export and take a note of the file name and location of the back up you're about to make - it may be crucial if anything goes wrong in the Registry.
Navigate in the way you would through the file system to this key:- H_KEY_LOCAL_MACHINE>Software>Microsoft>WindowsNT>CurrentVersion>WPAEvents. In the Topic pane, right-click OOBETimer, and then click Modify then change or delete at least one digit of the value and that will deactivate the current system.
To reactivate it and enter the proper (original) key, use Windows and R again to find the Open box, then type the following and click OK:- %systemroot%\system32\oobe\msoobe.exe /a
A form will show and you need to click on "Yes, I want to telephone a customer service representative to activate Windows" and then click Next. Click Change Product key and type in the key from the label in the new key boxes, and then click Update. If you get a Remind me later" message, type the command into the Open box again and see if you get the message "Windows is already activated".
Restart the system and all should be well. If at the stage of seeing the "Telephone Microsoft" message, you might want to do that and explain why you need help. They've never charged for that as long as I've been doing this.