Is the drive detectable in BIOS/Windows/Linux? If yes and if you have important data, try to back it up first on external pendrive/hdd etc. If your OS is not loading, try rescue disks or Live Linux distro to access the same.
If on Windows try running Crystaldiskinfo app. In case of linux/live linux explore SMARTCTL command to get the report on drive health. The SMART parameters will also indicate extent of damage in case there are any bad sectors.
Did the HDD/Laptop receive any physical shocks recently?
HDD Re-generator is a paid software and expensive. It's recovery works only in IDE Mode. If you do not have User controllable IDE/AHCI Mode settings for SATA Controller in BIOS and mostly if it's set to AHCI by the BIOS vendor, as the usual case may be, you may not be able to use HDD Re-generator to recover damage despite paying for the software. You will have to connect the HDD in question to a PC/Laptop that supports IDE mode in BIOS.
The trial version can however be used to get a visual map of the extent of damage(regardless of IDE/SATA Mode) . It won't allow you to recover though.
If the damage is less and collocated or contiguous you can give it a try by re-partitioning your HDD and pushing the bad sector area in un-allocated space. This trick may work or may not work depending on OS, HDD and extent of damage.
If Windows is booting try CHKDSK command from the command prompt. You can get the detailed options in its help CHKDSK /? or on the internet. Usually /F option tries to isolate the bad sector errors at a preliminary level.