I was watching my Toshiba 56mx195 DLP tv and heard a popping noise and the screen went blank but the sound was still on, is it the lamp or something worse?

SOURCE: My Toshiba 50HM66

i suggest checking the lamp. find you owners manual and go through the steps to "replace the lamp" if it is popped and you can see little pieces moving around inside than contact toshiba and they will send you a replacement with credit card numbers of course.

SOURCE: Toshiba 42 in 720 DLP TV MODEL HM66

You need to replace the lamp in this set. The "pop" you heard was the lamp popping.

Josh

SOURCE: Toshiba DLP Model 50HM66

You, more than likely, need a new lamp

SOURCE: toshiba projection tv

Sounds like it blew an "Internal Fuse"
if you want to fix it..simply open rear of TV and look for the fuse.
here is link for a manual if you do not have one.
Mastersage
http://www.devicemanuals.com/guide/Television/Toshiba/Toshiba-43H70-User's-Guide-TVRNME9EUT.html

SOURCE: 42" dlp tv has sound but no picture, replaced lamp already

Replace the ballast.