Hi im planning on buyin a laptop from a friend that the hard drive is dead in. Its kind of old and therefore has like a universal laptop hard drive pin arrangement on it. Now ive seen a lot on the internet about people using like these little adaptors to connect a laptop hard drive to a desktop computer, and i was wondering if the opposite of this can be done, connect a desktop hard drive to a laptop.

A desktop PC hard drive is bigger than a laptop hard drive, if wouldn't fit inside the laptop...

i dont care about size,, like i could connect the wires in some fashion to the pins... but wat i wanna know is would the laptop detect and be able to use the hard drive

Can't say that I have ever seen an adaptor to suit your needs. Not surprising really, a laptop HDD runs on 12V while a desktop also requires 5V which is not supplied by the laptop connector. I may have those voltages reversed but not the less, no power equals no go.

The 2.5 inch drive has a standard interface. Often manufacturers will place them into a caddy which changes the pin outs. This seemingly makes for a proprietry drive. Usually you can remove the old drive and put a new drive into the caddy.

Prices for laptop HDDs is still comparitively high but not nearly as bad as they were a few years ago. Spend the extra dollars and do it right. The advantage of a laptop is portability, something you will lose if ever you got that idea to work.