Computer formatting problem!

My computer's OS i.e. Windows 7 stopped working, I had tried everything like system repair/recovery nothing worked. Now I have downloaded the windows 7 Setup and trying to format. I have got and iso. file and burnt it into a cd. when I boot through that CD, the windows Boot manager opens and its says choose an operating system to start or press Tab to select a tool. The problem with my computer is that it keeps restarting. but now it doesn't even start the setup from the cd. Can you tell me what I have done wrong. I have a laptop too and I have tried booting the CD in it, same thing. The setup does not start, What should I do. You can ask me anything else you want. The problem can when the computer did not start i.e. that problem was in the hardware then, when it got repaired, the windows got corrupted. I want to know how I can start the formatting setup through my CD now and another thing is while booting there is no line press any key to boot from cd/dvd. there is just a blinking '_' and when I press something the windows boot manager opens. there is the OS windows 7 there which if operated restarts and I want to format my computer. it doesn't work in safe mode either.
If your answer work I will surely give you the best answer, and I used image burner software to put the .iso file to my DVD. Please help. :'(

So should I burn the .iso file or should I open the .iso file and then burn it?

If you have genuine Windows 7 with the license key and you have lost the original media, you can always borrow that specific version media from a friend and try to install Windows 7 from that.

To enter into boot menu,you may have to press a specific key - in most cases it is F11 or F12 - when the bios starts, and choose the DVD ROM as the boot device. If you have the motherboard manual check it.

What hardware was changed? Let us know so that we can examine how it could have corrupted the Windows installation and see whether the original installation can be repaired and brought to life.

What exactly did you do with that iso file? First you mention burning it to a CD, but I'm sure that Windows 7 setup is a DVD, it will not fit on a CD. At the end you mention DVD, but it does not sound clear.

What you should have done is to burn image to disc. The iso file is an image of the DVD, in this case the Windows Setup DVD. Any burning software would have the option to burn the image onto a disc. This is not the same as burning the iso file onto a disc, since what you want to have at the end of the day is a Windows Setup DVD and not a disc containing the iso file.

Apart from that, just as the other have said already, please let us know your system specs and try to describe whats happens more precisely.

Do you want to try to repair your old Win7 first, as we can help you do that.

Verify the integrity of the Win7 installation ISO or download another, use ImgBurn at 4x speed to burn to DVD (not CD). Or write to bootable flash stick using link below.

Then reboot computer and tap the one-time BIOS Boot Menu key given on first boot screen to select DVD drive to boot. Once you receive the "Press any key to boot DVD" prompt you will know the disk is bootable and it should load.

On second screen you can select Repair My Computer if you want to try to correctly repair your current installation. Accept any offered Repair, if none is offered but an installation is discovered, click through to Recovery Tools list to run Startup Repair several times. Report back findings.

If not, we can show you how to copy out any stranded files using this disk, or you can use free Paragon Rescue CD. Then follow the steps in the Perfect Reinstall link in my signature picture below.