I think Bitdefender didn't work and I need help ASAP please

aschit43

Shortly after blocking some malware, in the form of free plugins, and saying that it had succeeded I turned off my computer. It said shut down and update and I clicked. When I turned it back on again after starting up, and after the 'acer' logo, 'your computer is clean and your antivirus worked' was a message that popped up before I was allowed to log into it again. I don't trust it. This is the only computer I have and it has to last me at least four more years because I need it for school. Please anyone help me.