Reboot a site that Google has already indexed

Hello good time

My previous site was designed and done by a SEO company. Of course, I designed it at the same time.

Now the costs were high, I had to learn content production and site design myself. Now I am doing site design with WordPress.

My previous site crashed and I had to delete WordPress and reinstall it. It was also a Google index and I had a place in Google.

Now to redesign and launch the site. What should I do with the previous links? please guide me. I asked a consultant, he was just saying the word redirect. Now, if I redirect the previous links to the main page, will my SEO problem be solved temporarily ???

Or do I have to do something else? Do I have to do anything inside the console search? Or inside WordPress?

What can I do if Google does not give a negative rating to my site during this period?