However, recently I am not able to re-enter my wallet address in the browser, and no confirmation mails are sent by HashFlare.
If you re-enter the wallet address, withdrawal becomes disabled for 14 days, so you don't want to change that unless you need to.
If you are unable to modify the wallet entry, you should try different browsers which have no addons.
Send a support ticket in, because it's a long wait to get a response. If you are not getting emails from
alerts@hashflare.io, change your email provider. They are using mandrillapp.com to send emails which might get blocked as spam or you might end up on a rejection list if your address causes an email bounce.