first to answer your question, If your HDD is functioning perfectly with no failure, you can buy an adapter which connects your HDD to the PC via USB and you can access everything on your HDD. Just remember that your HDD will not appear as the (C) drive..
What the guy told you, don't completely believe that this would work because if you connect your HDD to another PC and can't get access to it, your HDD may have failed. If it does work then great you don't have a HDD problem but have maybe a Power Supply issue.
Now, when you say its "Broken down", are you unable to get past the windows loading screen? or are you just unable to power on the computer?
There are different diagnostic procedures if its one or the other. Failing to get past the windows loading screen can either be a Disk problem or a HDD problem.
Failure to power on the PC may be a PSU failure, even if you have noticed a split or crack in the wires. Wires are protected by a plastic sheath, now if its just that which is cracked/split, your PC can still power on. The only easy way to test a PSU failure is to swap your current one for a known working one or by using a special kind of equipment.
If you CAN turn the PC on but get the "Blue screen of death" chances are your HDD has failed. The only way I know of testing this is:
1)using a special kind of equipment that tests and detects problems on all sectors on the HDD
2) if the PC/Laptop displays an error message upon boot up (as mentioned)
If you can't power on your PC/Laptop, from recent experiences, I'd say its a Power Supply failure unless your cable has completely snapped. Let me know if you can turn on your PC or not and I will help you diagnose your problem instead of spending money to find out what the problem is. Instead of creating a long, long thread, PM me.