when does the statue of limitation start on a contract.

The statute of limitations on a breach of contract claim generally runs from when the contract was breached.  In NY, the statute of limitations is 6 years, except for sales contracts falling within article 2 of the UCC, in which case the statute of limitations is 4 years.  If the contract was a continuing one, and was repeatedly breached, each breach has a separate limitations period.  Thus, for example, let's say you breached a contract by failing to make payments in February, 2008 and July, 2008.  The statute of limitations would have run out on the February, 2008 breach, but you could still be sued for the July, 2008 breach.