Not likely anyone here. Best case would be a lawsuit if you feel the cost is worth it but even then the nodes are probably destroyed and re-used and depending on what was in the AUP/ToS legal action may be futile but that would require your lawyer talking to their legal department.

Getting the data back is unlikely and is a common rough life lesson about automating and testing backups. Exception would be if the most important data you need was publicly available and happened to be mirrored by the Wayback Machine [1]. Unlikely they would have anything useful to import into a database.

If I had to guess what happened the site was probably compromised and serving up something bad so they knee-jerk reacted by nuking the servers which their AUP/ToS may permit them to do unless you had a counter-signed business contract with them but I am not a lawyer and this is not legal advice.

[1] - https://archive.org/advancedsearch.php