how to learn to recover data manually

You need to explore the realms of backup your files. There are many ways to do this whether by simply copying important documents to diskette or CD-R's.

You can also backup your files by imaging or ghosting to another media--network drive, CD-ROM, separate hard drive.

Search for "RAID" on the internet for information about backing up sensitive server data.

Take a networking class at your community college--any class worth it's cost will include training you for back up.

There are also computer forensics sites that you can search on the internet that teach you how to retrieve data that has been previously erased--they are expensive, though. A few are:
http://www.forensics-intl.com/training.html

http://www.lc-tech.com/

http://www.vogon-computer-evidence.com/

http://www.ndci.com/Explorer/index.html

There are more, search Computer Forensics + Training and you'll see...
Best wishes!

Hi Kiran,
Backup is a broad term in your case. You will need to decide what you want to backup. Backing up a system might include
1). Making an exact image of the current state of the OS, so that if the OS fails someday, it can be restored back to this state. Eg: Norton Ghost

2). Backing up critical data on the m/c like, user code, important documents etc. Eg: Windows backup tool or Veritas Backup etc.

3). If it is on the server side, for example an MS Exchange mail server, then you will need to backup all the mailboxes; or if its a Database server you migh want to backup the entire database

The list of options are too many. So decide on what you want to backup and let us know. By being more specific on your requirements you should be able to get more ideas and answers.

there is a way to recover lost data...
look for it in microsoft website...~~~~~~undelete