What model computer and operating system? Not a lot you can do if  you can't get to startup repair and diagnostics or boot disk. See if this works-- How to use the Window Startup Repair Tool | Laptop Mag

You should be able to run Dell Diagnostics by quickly tapping F12 a few times.

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hi

kindly do boot startup check by press f12

I'm getting the same error,  diagnostics checked no error there but still getting the error message 

Please help anyone

Hi Rajat101

Please list Dell model number and version of windows. Example: Dell Inspiron 3543, windows 10

How to find the product model of your Dell computer | Dell US

In meantime, you change any of the settings in the BIOS before the boot failure message occurred? 

https://youtu.be/uJcqHY7YbmA