You should have when you first power the laptop on an option to choose the boot device on the fly.
There are two things you can try to get out of your boot loop.
Your first option is straight after you power your laptop on is to keep tapping the F8 key on the keyboard.
If this works you will be brought to a menu where you can choose how to boot the existing windows os installed on the hard disk drive of the laptop.
You also have the option to repair windows if it has become damaged or fails to boot through this menu and it`s select able options displayed.
First try a repair of windows via this method.
If you wish to boot off a Cd/Dvd disk placed in drive of the laptop.
As soon as you power up the laptop keep tapping your F10 key in rapid succession.
It should bring up a list of drives, where you select the cd or dvd drive and it should boot the cd/dvd you have in the drive so windows setup and install should then run from the cd/dvd inserted.