I'll take No for $100, Alex. You can recover data if you did a quick format (a short format writes over every block). But what happens then is that you have orphaned data sitting in blocks that are marked as not used. Recovery software can scan all the blocks and re-assemble files. If the blocks are overwritten with new data, like an OS install, then there is nothing to recover.
I've used software, "Recover My files". While scanning, it has shown lot of my files that can be recovered. But, Problems are, I don't have key for this software and files are of smaller size now (e.g my file of 2 GB is now being shown as just 200MB etc) .
Can I recover my complete files from these smaller size files??