Files with the .zepto extension are encrypted by Filecoder.Locky. These newer strains of ransomware are tricky to deal with especially when their encryption techniques are not fully known. Most variants seek to delete system restore points via the vssadmin.exe file so as to prevent system restoration and I highly doubt Filecoder.Locky doesn't do that. Decryption keys are only valid if the ransomware payload uses the same parameters for encryption from host to host but if it employs asymmetric encryption and pulls the public key for encryption off the C2 server for each new infection, then I am sorry. The best you can do is check within the reputable expert knowledge domain (e.g. security responses of Symantec, Eset, Kaspersky, VirusTotal, Malwr etc) to understand what type of encryption methodology it uses. Otherwise these other sites promising to decrypt your file might be taking you for another long ride and might victimise you in the end of it all.
I have got the files sorted in a separate folder. If you can post - what you suggest in a step wise procedure, it would be of immense help to me & many like me. Thanks and Regards.