In that case, you have to just look at the cards and read what you see in them by determining what cards there are the most of, for one thing. For instance, if there are a lot of Cups cards, the issue might deal with something emotional or with a relationship. If there are more Pentacles, then it may predominantly deal with issues like money, property, etc. If you're not an experienced reader, you may have a little bit of a problem at first with reading like this, but it can be done.
You as the reader, though, have the right to stipulate the conditions with which you want to read. If she wants a reading and your preferred method of reading is to have a question to go by, then just tell her that.
Also, you could just tell her that instead of a question, you'd like her to at least tell you whether the issue deals with work, love, family life, or something else. Then you have something to give you at least an area of focus and that helps.
Good luck. It's very common for a sitter not to state a question. As you gain more experience, you'll be able to work with that kind of reading more easily.