  A unified approach, for solving a wide class of single and many-body quantum
problems, commonly encountered in literature is developed based on a recently
proposed method for finding solutions of linear differential equations. Apart
from dealing with exactly and quasi-exactly solvable problems, the present
approach makes transparent various properties of the familiar orthogonal
polynomials and also the construction of their respective ladder operators. We
illustrate the procedure for finding the approximate eigenvalues and
eigenfunctions of non-exactly solvable problems.
