This has been a popular question lately, especially due to the "New Typepad" being released and being able to more easily and quickly view stats on your blog. So, the answer is that when the counte rwas put on your blog (using HTML code from your source, such as http://www.sitemeter.com/), you did not have the number of hits or visitors at that time and the counter started at 0.
So, to fix it, you can go into SiteMeter for example and from the Manager choose to Reset Counter. Enter the number to set it to, then you have to get the new HTML Code. Then copy and paste that code to your blog, replacing the existing SiteMeter code.
I'm sure there is a similar fix to other counters, or other counters, like SiteMeter, will let you set a starting count/number. So worse case, you can create a new counter and set the starting count to match the stats on your blog.
Best Wishes and Happy Blogging!