I got my test results back, i was looking at my pregnancy testing and my hcg came back as 24.9mlu/l then they tested my the nect day and it was 46.3mlu/l and my doctor told me i wasnt pregnant. could my doctor lie?

It is doubtful your physician would be lying to you. Without knowing more info, including ovulation date and how many days late your current cycle is, and when these blood tests were taken timewise, it is difficult to advise you. Here is more info on hCG levels: ref: https://americanpregnancy.org/getting-pregnant/hcg-levels/

Based on those results your doctor is incorrect, perhaps misinformed. This is consistent with a very early pregnancy that so far seems to be progressing. In a normal pregnancy the hormone levels double every two to three days and an ultrasound should be able to detect something in the uterus in another week or two.