Recently all emails shown are the previous month's only. How can I restore all emails from earlier both in webmail and windows live mail. I cannot recall doing anything to change the set up apart from a pc laptop (is this the problem?)
do you pay for premium email having left BT Retail?
Yes I do. Have done since leaving UK 11 yrs ago
Its possibly your account has been blocked.
See https://www.bt.com/help/email/what-is-premium-email-and-how-do-i-get-it-
"Customers who live in the UK with a UK bank account. Although we provide the ability the use the service outside of the UK, you must not use it solely for this purpose. If you now live permanently overseas you must no longer use the service and need to contact us >"
I would be surprised if your email account was blocked. If it was why would it only be missing some emails and not them all and presumably it is still working, just that the emails are missing?
You are not very clear when you say "I cannot recall doing anything to change the set up apart from a pc laptop (is this the problem?)" If by that you mean you set up a new PC/Laptop with Windows Live Mail then yes that may have caused it depending on how you set it up, such as an IMAP or POP3 account and or if you had previously deleted the "missing" emails from the BT servers while using another device. Without further information it is difficult to be more specific.
Unfortunately if emails are now missing and they are not in any of your folders, such as spam or delete folder when you check on webmail it means that they have been deleted off the BT servers and they can not be recovered.
BT may be able to investigate for you but previously when this has been done BT can only tell you which device triggered the deletion.
As you are a BT Premium email customer you should give the BT a call and ask for the BT Premium email help line
From outside the UK
+44 150 174 7714
Monday to Friday 8am - 9pm
Weekends and bank holidays 8am - 8pm
I would not volunteer that you are not permanently resident in the UK unless asked.