@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.
# Turn on (or restart) your computer.
# 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.
# A list of hard drives is displayed under the ***System Information*** in the ***General*** group.
Download the service manual for your computer [https://dl.dell.com/topicspdf/inspiron-15-5575-laptop_service-manual_en-us.pdf|from here] Page 127 and on will tell you how to check and how to set it up.