Your local computer repair shop should be able to help you.
To do it yourself, you will need another startup disk with an operating system on it. This would be another hard drive, or else a boot CD containing utility programs.
Once you have the computer running, the utility programs may be sufficient to allow you to read your ailing hard disk.
If your data cannot be seen, there are several disk recovery programs available for download from the internet. Usually you can use one to examine your disk for free. Then if it locates your data, you must pay money to unlock the program's recovery option.
If none of the above methods work, and you absolutely need to recover the data, there are shops which will disassemble the hard drive and use their equipment to read whatever data is on the disks. They charge a lot of money for this service.