Minecraft server won't connect?

I'm new to the whole owning my own server thing and i set one up a while ago and it worked fine but minecraft has been updated so i downloaded a jar file for the 1.8.8 server so its the same as minecraft but when i open multiplayer it try's to connect to my server but then after a few seconds red writing appears under the server name and it says "can't connect to server"

Can anyone help please, it'll be much appreciated.

Have you port forwarded the server if you haven't then thats why but if its just you playing just put "localhost" and that should work without port forwarding.