Minecraft says it has a invalid session when trying to go on servers.

"Invalid session (try restarting your game)"
That?
Restart Minecraft, you might (but shouldn't) need to restart the launcher.

Restarted it,still wont work. Are servers down?

You have to restart both the game and the launcher.

This is a technical support issue; this site is for bug reports only. For technical support please use the Mojang Support Center.

Sorry!