You should be able to recover your original base provided you had previously linked it to a recovery method like Facebook, Game Center (iOS Only), or Google (Android Only). Simply link the base you see when loading the game now to the same Game Center/Google/Facebook account you used for your original base; this should prompt you to choose between the two bases: the new one and your original. Make sure you pick the correct one as the one you do not select will be lost.
If you are having some trouble recovering your base after following the above steps, you will need to reach out to Customer Support. We will be happy to help; however, you will need to verify your account ownership by providing the following details:
-The approximate date the base was created
-The first device you played this base on
-The approximate date you last loaded the base
-Receipt from your last purchase
iOS instructions: https://support.apple.com/en-us/HT204088
Android instructions: https://support.google.com/googleplay/answer/2850369?hl=en
-The Player ID's for both bases; the one you see now and the one you are trying to recover
Open a new ticket and include the accurate account above information, then we should be able to see what needs to be done to recover the base in question.