some of my seeds didnt come up
Seeds could be old.
Wrong type of soil and moisture
Really need more info to help you out...
What type of seeds are they?
They are still in the packet. I know it sounds daft but there are more than one gardener who has had his/her concentration broken and put the packet unopened back in the pocket and wondered why the seeds haven't grown. I kid you not. Especially if you are planting a large number of rows of different veg. Wait for it YB yes I did just that with a packet of lettice seeds.
I have done the same thing, to many things going on, distractions.. then had to stop and think... did I put the seeds in or not?
Temperature often plays a big part in the growing of seeds. Different types of seed will grow in different temperatures.