I installed windows 7 now i have no sound.

If you look at the device list, are you even recognizing your sound devices? It is likely a driver issue, but without further information, there are 1000 reasons this could happen.

plese i want you to give me free
vista that i can use till i purchase one

plese i want you to give me free
vista that i can use till i purchase one

How about you go out and purchase a copy if you want Vista.

You will have to install your driver for your sound.

You will need to make sure that it works with windows 7, or do it in compatibility mode.

I installed windows 7 now i have no sound.

what is th name of your drivers is your sound card on your motherboard if so goto the web site of your motherboard
and down the driver from the web site