Solve, resolve, unfold, unravel, decipher can all mean to make clear or apparent or intelligible what is obscure or mysterious or incomprehensible.
Solve is the most general in meaning and suggestion in this group; it implies the finding of a satisfactory answer or solution, usually to something of at least moderate difficulty.
Resolve (see also ANALYZE ), as contrasted with solve, is likely to indicate analytic arrangement and consideration of the various phases or items of a problem or situation rather than finding a final solution or answer and is likely to suggest dispelling of confusion or perplexity by a clear formulation of questions or issues.
In some situations this process may achieve an answer, especially a ready or summary one.
Unfold implies continuous opening up, clarifying, and making more and more clear and patent until a full solution or resolution is apparent.
Unravel stresses the notion of making a clear and orderly rearrangement of something entangled or a simple ordering of something complicated, especially by patient endeavor.
Decipher stresses the notion of finding the meaning or significance of something very obscure, clouded, cryptic, or enigmatic.