If you still can’t fix your problem with the Start menu or Cortana, try creating a new local administrator account.
If you're signed in with your Microsoft account, remove the link to that account first by doing the following (otherwise see "Create the new administrator account"):
Press Windows logo key Windows logo key + R, type ms-settings:, and then select OK. This opens Settings.
Select Accounts > Sign in with a local account instead.
Type your Microsoft account password and select Next.
Choose a new account name, password, and password hint, and then select Finish and sign out.
Create the new administrator account:
Press Windows logo key + R, type ms-settings:, and then select OK.
Select Accounts > Family & other people (or Other people , if you’re using Windows 10 Enterprise).
Under Other people , select Add someone else to this PC.
On Windows 10 Home and Windows 10 Professional, provide a name for the user and a password, and then select Next. On Windows 10 Enterprise, select I don’t have this person’s sign-in information, and then select Add a user without a Microsoft account.
Set a user name, password, and password hint. Then select Next > Finish.
Next, make the new account an administrator account.
Under Family & other people (or Other people , if you're using Windows 10 Enterprise), choose the account you created, and then select Change account type.
Under Account type, select Administrator > OK.
Sign out of your account and then sign in to your new account. If everything is fixed, move your personal data and files to the new account.
To move your personal files from your old account to your new account, try opening File Explorer and looking in the Users folder, where you should see folders for both accounts. You can then copy and paste your files from the old account folder to similar locations in the new account folder. Or if you prefer, you can upload your files from your old account to OneDrive, and then sign into the new account and download the files from OneDrive.
If the problem still isn't fixed, try deleting the old administrator account:
Under Other users, select the old administrator account, then Remove > Delete account and data.
After the old account is removed, restart your device and sign in with the new account again.
If you were using a Microsoft account to sign in before, associate the Microsoft account with the new administrator account. In Settings > Accounts , select Sign in with a Microsoft account instead and enter your account info.