OS loading problem

Press F12 a couple of times at powerup.  Boot to the Dell diagnostics from the menu that appears, and run an extended (NOT just a quick) hard drive test.  Post back with the results, along with the system model, age and operating system and version.

The hard drive test will take about two hours - let the quick tests run, then boot to the 32-bit diags and run an extended (surface) drive test.

hard drive test is running. i shall reply you soon. plz wait and thanks for your help.

the result is it is showing " no problems have been found with this system so far. Do you want to run the remaining memory tests? this will take about 30 min or more" Model n4110, age almost 2 years, os was win7 and 8.

Press F8 continuously after powering on until you get the boot menu.  Then choose safe mode.

hard drive test result : success -all test passed

See if you can get into Safe Mode (F8 before WIndows begins loading).  If so, you can look at the event viewer to see if anything is causing the problem.  Worst case, back up your data and do a factory reset of the operating system:

www.dell.com/.../ArticleView

please reply, i am eagerly waiting for you reply. thanks

F8 is now showing or working.

F8 is not working but F2  and F12 are working, have any another option?

www.dell.com/.../ArticleView

how can do this?

Since you can't get in another way, you will need to do a restore to factory - that will return the system to the way it was when you received it.

thanks