Hi Mongo1981,
Please let me know the system model so that I can help you better.
Check if the hard drive is detected in BIOS. Restart the computer and tap F2 on Dell logo and check if the hard drive is detected.
Were any hardware or software changes made? How long have you been facing this issue?
Run diagnostics on the computer. Refer the following link to run diagnostics on the computer:
Awaiting your response!