Win8 presses F8 to start the repair computer option at boot time.

Win8 press F8 to start the repair computer option at startup. The method is as follows:
In Win7 and earlier Windows systems, press shift+F8 to enter “ Startup Options >; Windows 7 in the default installation, "Advanced Startup Options" is included in the "Repair Computer" option, you can enter the Windows Recovery (Windows RE) environment. If not, you can use CMD as an administrator under the system, type “reagentc //info”, press Enter to display some Windows RE information, and the value after the Windows RE” option is enabled. ;0”, when Windows RE is disabled, after determining that Windows RE is disabled, type the “reagentc //enable” command line and press “Enter” to re-enable Windows RE.
But, because Microsoft is trying to improve the boot speed of Win8, it is too fast to press F8, so Microsoft simply cancels the F8 boot “ advanced startup item. (In the middle of Win8-DP version, shift+F8 can be started, but The CP version has been removed) and the advanced startup option is automatically launched when there is a problem with the system.
You can also manually enter by the following methods:
1, Win key + i key, select more computer settings.

2, in the "General" option, the last "Advanced Start", select "Restart".

3, or when the normal selection restarts, hold down the shift key and restart.

4. After restarting, it is found that the “Advanced Startup Item” is also the Metro interface, select “Troubleshooting”.

5, continue, select “ advanced options & rdquo;.

6. Here you can see "Automatic repair".

7, start automatic repair.

8. Select the account that needs to be repaired.

9. Enter the account password.

10. Continue.