Wester Digital External Hard Drive

I have a Western Digital external 250 GB hard drive and it does not want to power on at all. The last time I used it it worked and now I tried plugging it in and turning it on and nothing happens. I tried switching out the power cord with another power cord to a different Western Digital external hard drive and still nothing.
I then went onto dismanteling it and seperating the chip which contains the power source switch... I was wondering if it was possible to purchase another chip for it and switching it out and trying my luck with that. If that's possible or if anyone has any other insight on trouble shooting this problem I'm having that would be great. Thank you!
-Jason