Hey there, @Bleumoon72
Bo here from Shopify Support!
So it sounds like the collection that you have deleted was listed on your homepage as a featured collection and so - when it was deleted it was also removed from the homepage. To rectify this I would recommend going to Online Store > Current Theme > Customize. You will then need to click on Featured Collection from the left-hand side and replace the collection you have listed here.
You may need to recreate the collection. You can read up on creating collections here.
It sounds like you are just getting started! I'd recommend taking a look at our Shopify webinars for sure. These short tutorials takes you through all the basics of creating a store such as adding products, variants, collections, theme changes and pointing a domain to your store. You should be able to sign up here.
Let me know how this goes and if there is anything else I can assist you with, I'm happy to help!
All the Best,