When you install Windows, you are prompted to enter the name under which he will work in the system. Account administrator remains invisible, it is possible to enter in safe mode. But it is possible to enter the name of the administrator and in normal mode, causing the login window in Windows during the boot process.
Open "start" - "control Panel" - "user Accounts" - "Change user login". Remove ticks with items "Use the welcome screen" and "Use fast user switching". Confirm the change by clicking "Apply settings". Now when you start the system will appear a window of Windows NT.
When the window appears, enter the name Administrator and click OK. If the account was not set a password, you are logged in as an administrator, i.e. with the maximum authority.
Account with limited powers are often used in organizations. If necessary to change something the employee is forced to ask the system administrator, which is not always convenient. So nothing in the system do not change, you can try to log on as administrator via safe mode.
Then restart the computer. At the time of system start periodically, about once per second, press the F8 key. In the window that appears, select the line "Safe mode". If an account administrator is no password, you are logged in as admin. Desktop in safe mode a bit oversimplified, but all the basic functions of the operating system are stored. Such input is useful if you forgot the password of your account: logging in as the administrator, you will easily be able to change it.
If the account is administrator password is set and you don't know, to log in under this account just will not succeed, you will need a special utility. For example, ERD Commander. Put it on a disk or on a flash drive and run at boot. Detailed instructions on using the utility is on the Internet.
Some builds of Windows, e.g. XP Zver, the installation automatically make you an administrator. For security you can create a regular account, switching between them will be carried out via the menu: "start" - "logout". When creating an account the system can suggest you to first create an account administrator. Create it, then create an ordinary entry, and the extra entry administrator remove.