Toshiba A15-S127 no sound; XP Home
It seems logical when we see the things that you have tried. I like to advice you to try use volume dial (physical), Use Ctrl+ESC to mute-unmute main sound channel. 3rd party registry editors are really dangerous for non advanced users. it might cause some severe issues. Since you claim issue happened after installation of the said software, you may use "System Restore" by choosing earlier date that sound worked fine. If issue persists, please post for more assistance. Also you may consider Full System Recovery by using Toshiba Discs.