Unable to reopen Completed Sprint or see reports in Next-Gen Project Type

[Learn and Build]

I accidentally completed my ongoing sprint, it had few tasks on which my team was working. Now those tasks are neither visible to them nor to me, not even in the Backlog section.

I want to re-assign the same tasks from that closed sprint by moving to a new sprint which I will be creating once I find those tasks or either I am able to restart the same sprint.

Kindly assist!

[Gunther]

I also wanted to reopen a closed sprint. The support section says in reports you will find the "sprint report". There you can reopen a closed sprint. But there is no sprint report. It seems that this applies for classic only. Suggestions for next-gen?