How long might these last?

From my Dad's house as we were cleaning it out:

Delgado Zuleta Cream Sherry
Hennessy VSOP Reserve Cognac
Arrow Creme de Cacao

All are sealed but show some evaporation and no doubt they've been warmer than they should have been on occasion. All are about 20 years old (+-).

Generally speaking cognac should do ok. Generally spirits survive (but don't improve). With creme de cacao's lower alcohol and additives, I'd be less confident. Sherry in general is not made to be aged once in bottle, but I know nothing of cream sherry

Agreed with Dale that the Cognac will be fine so long as it is truly sealed.

The cream Sherry will probably show well. Keeping in mind that cream Sherry (the favored drink of Sancho Panza), which is actually a sweetened form of Oloroso, is slightly thick and syrupy, deeper in color and even sweeter than the Oloroso it may have lost much of its sweetness but will have probably held well. As to the Delgado brand worth remembering that at their best, these can be delicious. At their worst they can be cloyingly sweet and far too much like syrup. At any rate, worth opening to try.

Also agreed with Dale's skepticism about the Creme de Cacao. What the heck, open it and try it. Worst comes to worst it can be your contribution to cleaning the local sewer system.

Best
Rogov

Thank you both, Daniel and Dale. I think the Cacao is going down the drain as I don't even want to try it. The others - as Daniel said, are worth a try.