Well if you had them synced or saved to a google account, they should be accessible from there. Or if you had backed them up to say a computer. However, if none of these are an option then there is no way to get them back.
That said, you can always try looking at your bill (if you get a physical one) or go into your account online with the carrier/service provider and look through your list of calls and texts. While it won't give you names, it will show you if a call was inbound or outbound and the length of the call. It will also show you (for both calls and texts) the date, time, and number.