Do you have your repair disk...? (Which I'm supossing u don't have)
If you have to follow this link...
http://www.howtogeek.com/96630/how-to-reset-your-forgotten-windows-password-the-easy-way/
Now the other way...
Can you get another bootable os through pendrive...
A bootable os is which you can run from ur pendrive,cd,sdcard,camera or anything that has storage...
Its always nice to have any os installed on ur pendrive (i would prefer ubuntu for biggners but you can anything you want... :) )
Go for 8 gb or higher pd for os installs...
You can carry your computer anywhere with you in 8 gb pendrive (Pd)...
Sorry i deviated from main topic but it is worth it...
So if you have bootable os say Ubuntu Linux(preferred)then open terminal...
Ahh wait I'll get the link...
http://www.chntpw.com/reset-windows-7-admin-password-with-ubuntu/You can find anything on internet :D
I came to know about chntpw when I was in class 8
I wanted to take down my floor incharges computer so badly... I had that kind of passion for getting into other people's system :)
Anyways hope it helps...
Want another way...
Just google it dude
"Just remember to take down networks Google is your best friend"
Any unsecured network shows so much info that u can just grab by google...
Anyways other left ways are either by bootable password changing disk as mentioned above by some one...
Or just asking the person who is the admin of the computer :p