The best way to determine whether it is an outage is to check the live status on sites such as Downdetector or StatusGator to see whether the reported problem is common to hundreds or millions of other people. If Snapchat is unavailable, wait until the services are restored, assuming, of course, that only you are experiencing issues. Then, restart Snapchat, delete the app cache, change the network, or even uninstall the application itself.