One of my friends whose Snapchat stopped working ask me the same question how I can fix Snapchat keeps crashing then, I researched it, and found some helpful steps which helped him and would definitely help you to fix Snapchat keeps crashing problem:
Try to clear the cache file
If your Snapchat is outdated then, update it immediately
You can try to uninstall and install the application
Reboot your phone might be helpful