My computer won't open windows.

It says we apologize for inconvenience but windows did not start successfully. A recent hardware or software change might have caused this. Blah, blah It won't do anything if I select to return to a previous good configuration or select windows to start normally. The screen Aldo counts down & goes to the Windows screen with blue bar & then to black screen that says Dell & then back to the screen I started on with all the text. What do I do???