Probably, your project is building to a 64bit target: there is no version of Jet for 64 bit machines.
You might be able to use the ACE 64 bit driver:
http://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=23734[
^] - but I have no idea how that would work if you need to go back to Jet for your 32 bit apps.
However, you may be able to switch the project to 32bit and use your installed Jet driver, it depends on what other assemblies you are using.
Maybe it's time to scrap Access databases altogether, bite the bullet and go for SQL server instead?