Why my Dell laptop is not starting its on and showing Dell logo?

@ibrahimkha93435 could be that your computer cannot find the OS. You want to start off by checking your BIOS to see if your BIOS can see a boot device.

1. Turn on (or restart) your computer.
2. During POST, when the DELL logo is displayed, watch for the F2 prompt to appear, and then press F2 immediately. NOTE: The F2 prompt indicates that the keyboard is initialized. This prompt can appear very quickly, so you must watch for it, and then press F2.
3. A list of hard drives is displayed under the System Information in the General group.

Download the service manual for your computer from here Page 127 and on will tell you how to check and how to set it up.