Consolidating multiple spreadsheets

Hello, so my boss wants me to take 3 years worth of spreadsheets and consolidate them. He doesn't want all the data, just account name and $ totals. Now, the problem that arises is that not all accounts are present in each spreadsheet month, and my boss wants all accounts within the last 3 years to be on one side, regardless if they purchased anything in some months, and monthly totals of each account in ascending order. So for instance:

column A will have account A (row 1), B(row 2), and C(row 3) . column b would be january 2008, and column c would have february 2008. Lets say in january, all three accounts made purchases, but in february, only account A made a purchase. This means accounts B and C will be zero

It is going to take me forever to do this manually, as I can't copy and paste the data as the accounts change every month. Is there any way to make a formula or something? I would GREATLY appreciate it.