Your phone will not work abroad unless you have the roaming facility active, which enables a connection to foreign networks - without which, you won't get coverage outside the UK and thus be unable to access calls, texts or mobile data.
This is normally done by texting ROAMING to 150 before leaving the UK, or by calling EE CS. Did you do either of these?
If not, your only recourse now is to contact CS by another means, to request roaming is activated. Either from another working phone, or from a web-calling app such as Skype.
