My pictures disappeared from my Nikon?

I have a Nikon d3400 that I've been using often, and there was about 2000 pictures on it. Today I went to take some more pictures and after a few minutes I noticed that the picture count was only in the 30s. All my pictures disappeared and I don't know how. I haven't touched the memory card since i first put it in. How can I get my pictures back? And do I need to get a new memory card before taking more pictures?

Take the card out of the camera and see if a computer will read everything on it.

If not, try a data recovery program.

Do Not Format The Card!

"And do I need to get a new memory card before taking more pictures?"

YES! Any new pictures you take might overwrite the existing ones. I don't know what's happened to your card but it's very unlikely that something's destroyed all the data on the card. Recuva's a popular data recovery program though I've found PC Inspector Smart Recovery to be more powerful (but a bit more difficult to use). Both are free.

Stop using the memory card and use Recuva to try to recover what you can from it.

Next time, after a day's shoot, copy all photos to the computer and a second backup to an external hard drive or CD/DVD. Memory cards don't last forever.