i incautiously deleted some content in /etc/modules.conf is there any software to find them back? thx!

What editor did you use?
Many of them make backups
automagically.

Try
ls -A

and see if a file named very similarly to modules.conf exists

Edit:
For the future always make a back up of system
files before you change them. That way if you
completely trash your system you just need to
pop in a recovery disk and copy the backups to
the appropriate place.

When I first started using Linux I did a rm -rf ~ by accident.....how did I do that by accident, I don't know. I was a stupid newbie. I found out that there are two ways to get the information back. 1. Using the tool mc or midnight commander you can try to piece the files together from your hard-drive if the space that they once occupied has not been written over by the creation of new files. This is extremely difficult and will take hours and hours of frustration and you might not get anything out of it. 2. You could send your hard-drive off to a company that specializes in data recovery and spend thousands upon thousands of dollars to retrieve the lost files.

As number 2 is out, unless of course you are some sort of millionaire who likes to waste money. Then you are left with number 1. You could try it, but speaking as someone who tried this once. Just forget about it. It is not worth your time. Sorry, it sucks I know. I am sure there is someone on this forum who can recover lost files, but it is not something that is easily taught in a few lines on a web pagte. They would no doubt have to be sitting right there with you and even then there is no guarantee that they will be able to recover the files.

Later

i used vi. and i solved the problem in other way --- get a same config file from internet and edited to mine. stupid but rapid way for me. thank you for your advice. i really got this lesson.

i m not sure if there is going to be any other problem occurs in furture. need to see