How about showing us the actual command(s) you tried, so we can point out where you went wrong?
The most likely culprit however, is that the slashes in the text conflict with the slashes in sed's substitution command. This is easily fixed, just by using a different delimiter (you could also backslash-escape them, but why bother?).
Code:
sed 's|/home/dinesh/scripts|/var/tmp/scripts|'
Here are a few useful sed references.
http://www.grymoire.com/Unix/Sed.html
http://sed.sourceforge.net/sedfaq.html
http://sed.sourceforge.net/sed1line.txt