Note that you don't have to try 2^256 times to crack an address' private key instead of the specific private key that was generated, but rather 2^160. The address is an encoding of a RIPEMD-160 hash result which is 160 bits (along with a network byte and a checksum). This means that for each address, there are around 2^96 valid private keys.

Data encrypted with the private key cannot be decrypted by the public key in asymmetric encryption.