<p>We have a 12-year-old Ms Access app that we use for our core inventory warehousing and invoicing system. It IS already running on an SQL Server backend, but all the "logic", forms and reports are in Access. After experiencing the massive amounts of maintenance sludge it took to turn inventory transactions from non-temporal to temporal, I realized that I need to someday convert this thing into code so I can better manage the logic in a much more maintainable and testable environment.</p>

<p>What are some techniques that would allow me to convert it into a .Net application in a manageable and efficient manner?</p>

<p>One idea was to convert the queries to stored procedures, then convert the app into an Adp project.But I am still clueless as to how to handle the forms and reports.</p>

<p>Also, I am the only developer for my company, if that matters.</p>

Short answer: the migration doesn't seem like something easily automated.
My guess is that your best bet is to rewrite (and install) the system one piece at a time, even if (perhaps) it forces your users to run the old and new versions side-by-side for a while to use different bits of functionality. You can minimize that hassle by careful consideration of which features to migrate and in which order.
For example, you might have one user whose job role requires him or her to use just one screen all day. If you migrate that screen first with accompanying functionality, that user can be on the new system immediately and leave the old one behind, reducing your maintenance load.
So those are just some ideas based on not too much information. I hope this helps anyway.