Serious problem!

[محروم.كوم]

Having some real trouble and I have absolutely no idea what to do. The site was running fine for a long time and suddenly I was made aware by some of the members that they could no longer post. They, and I, keep getting the same error message: The message you have entered is too short. Please lengthen your message to at least 1 characters.

I also noticed that I could not use the “smilies, and with that, I figured that there were also probably some other problems. However, I never really had a chance to investigate further as about one hour later I could no longer access the site! When I now go to the site I simply get a blank page that says;
Fatal error: Call to undefined function cmps_template_alter() in /home1/bonsaic1/public_html/includes/functions.php(2953) : eval()'d code on line 3

I’ve not changed anything, and or added anything into my site in years so I’m totally stumped. I’m still running on 3.8.4. I’m also admittedly totally ignorant on the technicalities of updating or loading files as I’ve always paid to have it done, or was lucky enough to have gotten some help in the past. At this point in time I’m really desperate here! Help!! __DEFINE_LIKE_SHARE__