I've been told by my daughter's teacher that she hasn't been attending school for the last two weeks. What should I do?

Be concerned. Your daughter is obviously hiding something from you to be able to deceive you for this long. The real question is to find out the cause. It may be worrying to find out where she has been spending her time and with who (if anyone) has been caring for her, as well as determining why she’s been avoiding attending in the first place. Is there an issue of bullying; isolation, or peer pressure caused by either her classmates or her teachers that needs to be addressed? Has there been an issue at home that’s made her lose her faith in people altogether? Is she being threatened or manipulated into doing something that’s against her will? Or does she think that she’s scored a secret advantage that no longer requires her to follow a development path alongside her peers? Whatever happens, there’s two major things that needs addressing, either by talking to her or observing her to see what develops.