Assuming you are using new gas. Now get a new spark plug, NGK b7hs. Leave the new plug out at first and pedal for a while to dry out the motor. Then put in the new plug and try again.
If you get some little pops or it seems like it wants to run while your pedaling well then you then need to get a compression tester and get a reading . Could be the bike was seized before you got it and the compression is no mo (edited)