By mistake, I deleted a file using shift+delete. The file is extremely important. Is there any way to recover it?

Check your recycle bin first to see if it is there.

Usually that command deletes the file/data from the disk.

You will have to purchase a recovery program. And it may not work as the drive area might have been overwritten already.

Links for more information:

http://support.microsoft.com/kb/239754

This a paid for recover link:

//www.windowsdiskrecovery.com/blog/shift-delete-recover

I've used the above. It works about 60% of the time.
It's not a live link as I won't flog the product.