Hi @halaalizeinab15 
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Thanks for reaching out! We can’t tell you who is managing your account but i’m sure there are some databases you can use to search and reach out to that member directly. If you would like to retrieve the domain you will need to prove you own it by setting a txt record.
Please verify domain ownership and let us know by responding here when that’s done. If the verification is successful we can remove the domain from the other account so you can use it on yours.