Enable Administrator account Windows 7 Domain

First thing you will do is boot your computer in Windows 7 and Choose Repair your Computer as shown below

Figure1

Then it look for available operating system and let you choose for a compatible OS then click next

Figure2

In System recovery option choose Command Prompt

Figure3

In your Command Prompt type regedit and it will show the image below. 

Figure4

Click HKEY_USERS then go to file tab then Load Hive

Figure5

In your Load Hide window look in the drive that is shown in Figure2, in my case it is in drive D:\Windows\System32\Config then select SAM, click open

Figure6

Then type SAM_TEMP and click ok

Figure7

In your registry editor go to HKEY_USERS\SAM_TEMP\SAM\Domains\Acount\Users\000001F4 then double click F

Figure8

Change '11' to '10' located in row 0038 as shown below then click OK

Before

After

Click SAM_TEMP then in your file tab choose Unload Hive and click yes

Close Registry Editor and exit the command prompt. In your System Recovery Option Window click Restart. When the computer is connected to domain just type .\Administrator and hit enter.


Reference:
Best Practive: How to enable a disabled Local Administrator account offline in Windows 7 (even when using BitLocker)