If i took a digital pregnancy test it came out saying pregnant then the next day it's says not pregnant what does that mean?

Well: Try it again for sure, you may be early and some variation between the devices is making the difference. You may have been transiently, lost it very early which happens often. People know more now, quicker b/c of the sensitive test, or the first reading was wrong. Logically these seem to hold all the possibilities just check again in a day or 2.