hello friends

i am very much new to linux.i have both win98 and red hat 9 on my PC
i installed NS2 in linux,but the help that i referred asked me to make the following changes in

~/.bashrc file that is located in the /home directory where ns2 was installed

export NS_HOME=/home/UserName/ns-allinone-2.26/
export PATH=$NS_HOME/tcl8.3.2/unix:$NS_HOME/tk8.3.2/unix:

$NS_HOME/ bin:$PATH
export LD_LIBRARY_PATH=$NS_HOME/tcl8.3.2/unix: $NS_HOME/tk8.3.2/unix:\

$NS_HOME/otcl-1.0a8:$NS_HOME/lib:$ LD_LIBRARY_PATH
export TCL_LIBRARY=$NS_HOME/tcl8.3.2/library

after this when i restarted my computer its giving error in this file
and is not allowing me to login(the error message is shown after i enter my username and password)

what should i do to overcome this problem?

thanks in advance

Login as root (you haven't forgotten the root password I hope? ) and then remove the changes you made.

sir
i logged in as root only.
it accepts my username i.e. root,and password but after this it shows an error message ask me to login from failsafe session which i tried but the same problem persist.
once this error message is displayed it gives me to choices
1st choice gives the changes that i have made in it
and 2nd is "OK" button and on clicking that button the system again shows me the login screen

In the wrost case you can try to boot from your OS rescue disk and after remove the changes you have made.

Note : NEVER use root user for common use. NEVER