Laptops General - Read Only

[msvv]

I replaced my WD 250GB RPM 5400  with a WD 500GB RPM 7200 and I  get a "No boot sector on internal hard drive"  "No bootable devices" I have both original disks ( Operating System  Windows 7 and Applications.) I put the Operating System CD in and started the computer than I hit F12 went to CD/DVD and hit enter I received the message "No boot sector on Internal  hard drive" "No bootable devices" What am I doing wrong?

[DELL-Vikram M]

Hi msvv,

Please share the system model. Make sure the hard drive is getting detected in BIOS. To enter the BIOS (system setup); restart the system and keep tapping F2 as soon as the Dell logo appears. In case the hard drive is getting detected, put the disk and try re-installing the operating system again. When you get the message 'No boot sector on Internal  hard drive', you should get an option to press F1/F2. Press F1 and see if that makes a difference.

Keep me posted. Please reply for any further questions.