Hi, I'm not sure if this is the right spot, so if it's not, someone can move it.

Anyway, about a year and two (three?) months ago, I bought a Marshall JCM 2000-DSL 401 Combo amp. Everything up until the past month or two has been working great.

About a month ago, however, I noticed that the amp lost all output. By that, I mean that the amp itself functions fine, it turns on, off, everything works, but there's no sound. I'm not too knowledgeable about this type of stuff, so I'm not really sure why.

I plan to take it in to my local guitar shop and they'll look at it for me, but any help before-hand would be great.
You most likely need to replace the tubes. Tubes die out after 2-3 years generally.
If you're not too familiar with tubes in general, check out the ''Everything you ever needed to know about Tubes thread''... the titles something like that.