The answer depends on the circumstances of your account(s) and where you’re trying to pull the data from.
We began transitioning U.S. advertisers from our old DirecTraffic Center (“DTC”) account management platform to the new “Panama” platform in October 2006. These upgrades continued in the U.S. through approximately April 2007. (Other markets, including the UK, began later.) In all markets, data contained in the DTC was retained for access by individual advertisers for 13 months from the date of their upgrade to Panama.
So, if you are trying to access data from the DTC and it is more than 13 months since your upgrade to Panama (which is likely), that data is no longer available to you.
In the Panama account platform, the majority of reports can only access data up to 13 months prior, while others can go farther back (potentially, to the date of your transition to Panama.)
Finally, if an account is inactive for 13 months or more (no impressions and no clicks), the account is subject to closure, and all historical data is deleted.
Hope this helps.