Tennis star Melanie Oudin will be in Newtown Wednesday to give a tennis lesson to children in the town’s recreation program. It is the latest in a series of appearances by famous athletes after the December mass shooting at Sandy Hook Elementary school. The event was planned before the first selectwoman recently announced that Newtown would be turning down future invitations for special events there. Pat Llodra says the community wants to enter a ‘‘period of quiet’’ and return to some kind of normal routine. Oudin will be joined Wednesday by teaching professionals from USTA New England at Dickinson Park. She also will help announce the field for the upcoming New Haven Open tennis tournament, which takes place in August at Yale’s Connecticut Tennis Center.