OK. Don't give up hope.
Here are some more things you can test.
The RPi will boot without any display or any peripherals connected, I often have it connected with just power and a LAN and remote connect to it. So try this:
1. Insert your SDCard (ensure it is firmly inserted, and the end is touching right up to the black holder). You should see springy the metal contacts are pressed together too.
2. Connect power and watch the lights. You should get a power light, and within the count of 10 the OK light should start flashing (you may even notice a very faint flash when you first plug in the power).
If that happens, then you are getting somewhere. If not, then it can only be the SDCard, the PSU/cable, or the RPi itself which is wrong.
Now if you have wired network, you may be able to remote connect to it. You'll have to follow the instructions on here (I can give additional help if needed):
http://myraspberrypiexperience.blogspot ... p-vnc.html
I would suggest trying to connect using SSH first, as long as you have a wired network and you can look up the IP address on your router, you just need to rename boot_enable_ssh.rc
on the SDCard. Then you can use SSH to connect.
If you can do that, then it seems like your RPi is working PSU and SDCard, which would suggest a bad HDMI cable or display problem. Let me know how you get on!