Are you forgot your Windows xp/vista/7 login password or want to crack some one else password then their is a very simple to use hacking tool called Cain and Able that should be downloaded from HERE.
If you want to crack someone else login password then you have with the password hashes from there PC to crack. The hashes in Windows stored in C:/Windows/System32/Config/SAM file and in LINUX it is in /etc/shadow file. You will not be able to copy these files when you are booting same system. So you have to copy that hashes physically by just booting to some live LINUX OS like OPHCRACK and copy the hashes files, then give them to Cain and Able to crack.
Cain and Able is a simple tool that support many cracking methods of different hashes like MD5, SHA1, WPA/WPA2, WEP, LM & NTLM hashes include dictionary attack, Brute-force attack, and hybrid of both.
So know i just show how to crack hashes with Cain and Able. I will crack my own system password hashes.
Firstly download Cain and Able from HERE then install it and Run it as administrator. Then go to Cracker tab and click on + button over there.
Here I just import hashes from local host, you can also provide hashes from text file or from SAM database file.
Now the Brute-Force attack menu is open and you have to provide the charset to use and the max length of password is important here. I suggest to keep min length to 1 and max to 10 as some people use there Mobile number for there password.
So here my password got cracked by Cain and Able in few seconds.