You can bring back Vagaro services you've deleted. Just go to the Services/Classes Menu. Select the services you want to add again. Then, you're set. Keep in mind this does not pertain to custom services. So you will have to recreate them.
Helpful Information: Bringing back a service does not restore its initial settings, such as pricing and configuration.
Click on this link to learn how to add services in Vagaro: How to Add Services.