If you have NOD, and it's properly installed, then you don't have a virus.
To run a virus scan, click the pale blue eye-shaped thingy in the system tray, choose computer scan.
Select In-depth scan
Tick Operating memory and any local drives (such as your C drive)
Click scan
Rojash is alost certainly right ... what makes you think you have one?
It's true that no scanner is 100% - and it's possible that you caught something new before the latest definitions went out .... but unless you visit really dodgy sites ... it's unlikely
maybe it nodded off (I'm sure that option's been mentioned elsewhere?)