Recover bitcoin wallet with old Private Key about 3 years ago I created my bit coin  wallet and purchased few bit coins. I have done couple transactions with my wallet paying for things I bought in the internet.

I have no record of my wallet

I do have my private key

Recently I tried to import my private key in blockchain.info and got the message Invalid private key encoding 

I know for sure that this is my private key

I will appreciate any helpin explaining  what could be the reason for this error message

Also, how I can see transactions done with this private key

..and ofcourse any ideas to recover will be greatly appreciated
The problem might be that blockchain.info wants the WIF (wallet import format) instead of the private key. You might try to find some tools for converting the keys you have in WIF and then try to import them.

Make sure not to give away your keys in the process of converting (I wouldn't trust online tools)