A. Not without some help. Take a look at your publishing agreement to see if there are sales performance requirements written into the terms. But if you don't find a suitable condition, you can still ask your publisher nicely.
Most publishing agreements have several provisions that allow you to get your publishing rights back.
First, most agreements have a time frame within which the publisher must publish your work after acquiring it. Eighteen months is not atypical. In other words, a publisher can't buy your book and just sit on it. Now, if you turned in your manuscript late or it has not yet been made acceptable through the editing process or there are some other extenuating circumstances, they (the publisher) are probably protected from surrendering rights to you.
Second, most agreements have an in-print provision. If your book is not available for purchase and you bring it to the publisher's attention - in writing - with a specific request to rectify this by reprinting the book, the publisher must send the book back to press within a defined period of time or return publishing rights to you. Just to repeat, the onus is usually on you to initiate the process in writing. Now, this has increasingly become a point of contention between authors and publishers in the digital age. Why? In many agreements, offering a book in a downloadable e-book form qualifies as a book edition. And further, digital publishing means that the publisher can economically transition from offset printing to print on demand. In other words, your book will technically never be out of print even if nothing much is currently happening in the area of sales and marketing.
Third, a few agreements have qualifiers like a set time period for publishing rights or a minimum number of annualized sales or the requirement that it be included in a printed catalog. If you don't remember this coming up when you were negotiating a contract, then this probably doesn't apply to your agreement!
My book was printed on time and is still in print. It just isn't selling like I thought it would. This is so disappointing.
Even if none of the conditions apply, go ahead and ask for a reversion of your publishing rights, but don't be surprised if the answer is no. Or if the publisher encourages you to do some marketing activities that will help rekindle demand for your book in the marketplace.
Now, if sales of your book have steadily waned to next to nothing, if you have earned out your advance against royalties (or you are willing to pay back unearned advances against royalties), if inventory levels are low (and especially if you're willing to buy the remaining copies in stock), and if there isn't sufficient demand to warrant an offset print run (let's just say about 1,500 copies), then your publisher just might shrug his or her shoulders and say sure, you can have your publishing rights back. Often, the publishing agreement specifies that in such cases the publisher will let you have any plates, films, and files free or at publisher's actual cost. With plates and films becoming obsolete there is usually no or little cost associated with retrieving the electronic files. (Though that doesn't mean anyone can easily put their hands on the most up-to-date iteration.)
But again, even if all the circumstances of the previous paragraph are present, many publishers (self included) are loathe to return rights. Why? They (we) have invested a lot of money into publishing your work and as distribution technology changes and morphs into podcasts, e-books, print on demand solutions, and more, they don't want to lose opportunities to recoup their investment through new means of exploiting your work.
And one final question for you to ask yourself. What can you do to promote sales that the publisher hasn't done or won't do? If the answer is "a whole lot more" then get busy and drive sales without the manufacturing and inventory hassles. Or, if you have an iron-clad way to sell your own books directly, like a speaking schedule, ask nicely for your rights return and hope for a yes answer.