What is the OS and version of the UNIX box? That helps in giving correct information of how to turn on telnet (although it's not recommended - using telnet may be a security risk - ssh would be a better choice).
In general, you need to find the file where services are set up to start - (on Solaris it would be /etc/inetd.conf) - make sure the telnet line is not commented out with #.
and it is not in comment among all there is:
#
# Syntax for TLI-based Internet services:
#
# <service_name> tli <proto> <flags> <user> <server_pathname> <args>
#
# Ftp and telnet are standard Internet services.
#
ftp stream tcp nowait root /usr/sbin/in.ftpd in.ftpd
telnet stream tcp nowait root /usr/sbin/in.telnetd in.telnetd
#
# Tnamed serves the obsolete IEN-116 name server protocol.
but I can not telnet and I know it is more secure to use cecure shell but..I use telnet.
still telenet does not work for some reaseon
PS also I can ftp to local Uxix from my windows so ftp works.
are you using the actual microsoft telnet client? if so, i've never seen it work a good connection to a windows box ... try opening a dos window and then using that to telnet to the unix box ... also hyperterminal (see Start->Program->Accessories->Communications->HyperTerminal) would be good too ... good luck!