Sim not working

[Dhu]

My sim has stopped working. What do I need to do to fix this or who to contact without going into the shop 

[Tybricks]

My sim has literally just stopped working too

[Bambino · Accepted solution]

@Dhu, @Tybricks You need to speak to customer service.
Call 0800 032 1402 from any phone or numbers in this link: Guide: Coronavirus Community Help and Support 
When it comes to the reason you are calling, stay silent for 15 seconds and you will be taken to the keypad options.
Press 2 for Everything Else
Press 5 for More Options
Press 7 for Anything Else which will put you though to someone.
Say 'Upgrade', 'Lost/Stolen', or 'Fraud' if the suggestion above doesn't get you through.
Best time to call is 8 am.