Go to desktop and right click the time in the notification area and select 'Adjust Date and Time'. In the pane that opens, under the 'Date and Time' tab set your time and time zone ((UTC) Dublin, Edinburgh, Lisbon, London), click apply. OK. Re-open and select the 'Internet Time' tab. I have mine set to synchronise with 'time.windows.com'.
What is ransomware and how do I protect my PC from Petya?