The Laplace inverse of a function may not exist. A sufficient condition that I know of sets strong restrictions on the growth rate of the functions. Nonetheless, it does not mean that a funtion won't have a Laplace inverse if it does not satisfy the conditions. One thing that I can assure you that the functions you listed are not guarrantted to have Laplace inverses by any theorems that I saw. Therefore, only the God is with you when you do it. Attached is a try to the first function and apparently, you have to carry out all step in the paradise of distribution (generalized function). Even worse, it does not guarranttee a round trip if you try to Laplace the function again.