http://www.dell.com/support/article/us/en/19/SLN151713/en

:emotion-2:

1. At the black screen, try pressing "CTRL+SHIFT+ESC" to start Task Manager

2. At the top of the(Task Manager) page, click "File" then click on " Run New Task"

3. Type ‘msconfig’ and then select ‘OK‘ to open system configuration.

4. Click on the ‘tools‘ tab, select System Restore (Restore Reset to Earlier Date),choose the earliest date then click ‘OK’