Calculate Unspent using private keys Can we calculate unspent of addresses which are generated from other node server if we are having private/public key of those addresses?
If you have just a pair of private and public keys, you would need a little more information.

A single public key can control Bitcoin in a number of ways:


A direct p2pk output
A p2pkh output paying the hash of the public key
A p2sh output paying a script controlled by a set of public keys that may include keys other than the one you have
A p2wpkh segwit output paying the hash of the public key
A p2wsh output paying a script controlled by a set of public keys that may include keys other than the one you have


Without knowing which type of output you are looking for, the public key alone is not sufficient, especially for p2sh and p2wsh outputs where other keys are required to construct the address.

Once you know which output type to look for, you can use the scantxoutset RPC method of a node, or construct your own index similar to an explorer or Electrum server and query balances.