1. Press WinKey + Q, type user accounts and click on the result.
Lost Administrator Rights 1
Then select your User Account > Click Manage another account.
Lost Administrator Rights 2
In the following window, click Add a user account option.
Lost Administrator Rights 3
2. Now we have to create a local account user. So after clicking Add an account, click Sign in without a Microsoft account (Not recommended), then click Local account. Fill the details on the screen so appeared for adding local account. Click Finish when done.
Fix-Lost-Administrative-Rights-In-Windows-8.1-1-2
3. Press Windows Key + Q and type cmd, for the search results, click Command Prompt. Type following command and hit Enter key:
shutdown /r /o
Fix-Lost-Administrative-Rights-In-Windows-8.1
4. The previous step will result your system to boot into Safe Mode. After getting into Safe Mode, press Windows Key + Q, type user accounts, and pick the same from results so appear. You would have now two accounts on your system; first your issued admin account and second the local account which you’ve created in step 2. Select local account.
Fix-Lost-Administrative-Rights-In-Windows-8.1-1-4
Now click Change the account type link in following window:
Fix-Lost-Administrative-Rights-In-Windows-8.1-1-3
Moving on, change the account status from Standard to Administrator. Click Change Account Type.
Fix-Lost-Administrative-Rights-In-Windows-8.1-1-5
In this way, the new local account we’ve created has been changed to Administrator. Now you can restart you machine and log into this account with administrator rights. Since you have administrative privileges now; so you can backup your documents from the old administrator account.
Finally, delete the old admin account and switch to Microsoft account to synchronize your settings with new administrative account. Your system will now act normally with full admin rights in your hand.