@Wh0-Am-1 bro i am too facing this same problem...
as of now you simply cant retrieve your lost tabs and nobody here can help you ,you have to be prepared next time by use of session buddy or other 3rd party extensions.
here real developers will never heard our problems as some shitty moderators keeps on banning people for simply asking question in both opera+opera gx browser twice(you people are so active in noticing this type of errors but will never understand what a user is going through ..why not you help instead or dm personally to remove /modify the new thread)