Get the latest version of the messenger programm you use. Install it.
Often, security updates makes older version unable to connect. This apply to every messenger programms, so your failure to tell whitch one you use is a non-isue.
If installing the latest version don't solve your isue, ask again here with exactly what programm you actualy use, including the messenger name and version and what operating system you use.
Electro, February 2013
