How to recover the deleted files from the folder in linux?[Note:i had accidentally deleted the files from the folder by using linux command rm *.pl].How can i recover those files back using linux command?

Many text editors keep backup files. If you are really lucky, there might be something like yourfile.tex~ including a previous version of your file.

install testdisc and use photorec command. 

Good luck

  & hat ?install testisk linux with this command sudo --testDisk so that good is that work 

I found the below post helpful but to answer it here is little complex. Recovery generally require expertise, if someone try to recover without improper knowledge can experience more damage.

http://www.cyberciti.biz/tips/linux-ext3-ext4-deleted-files-recovery-howto.html