I found the solution (working for me!) and I recevered old datastore.
Probably the problem was because new ESXi install is in another harddrive and previous install was in the same drive of the datastore
So, I list the datastore with command:
esxcli storage vmfs snapshot list
[root@localhost:~] esxcli storage vmfs snapshot list
512ffa9c-b397085c-5a0f-d89d6729b62c
Volume Name: SAS_15RPM
VMFS UUID: 512ffa9c-b397085c-5a0f-d89d6729b62c
Can mount: true
Reason for un-mountability:
Can resignature: true
Reason for non-resignaturability:
Unresolved Extent Count: 1
after, I get the VMFS UUID and:
esxcfg-volume -M 512ffa9c-b397085c-5a0f-d89d6729b62c
Persistently mounting volume 512ffa9c-b397085c-5a0f-d89d6729b62c
And old datastore is added and works perfectly.