Help Needed Please , With Galaxy Samsung Phone

[pusskin]

i have a pay as you go, Samsung Galaxy Young phone.
This last two weeks it has played up. Not being able to send texts, coming back as failed. Son has text me several times and i havent recieved his calls or texts.
Have no idea whats wrong, and even Tescos hasnt resolved this problem when i took phone in a while back to ask for their advice.
I'm not clever with these these, so please explain in very simple terms.

Cheers Abers of any help you can give me.

(Tescos just took battery out for me and then put it back)

[Spannerfiend]

Have you tried a factory reset? Is it still under guarantee.

Factory reset will be in your settings, probably under security.