There have been previous threads asking this question, if you use the forum search facility these will come up @wippa_2
Vodafone have this support information on the website How to I reactivate my PAYG SIM?
Unfortunately, if it's been longer than 180 days since the last top up and chargeable connection Vodafone will have disconnected the SIM from the network. In fairness to Vodafone they would have sent texts notifications before disconnection.
However, no harm asking Vodafone the question drop the Social Team a message by following this link Contact Us
