NEED HELP! about Voltaic cell?

No, because a galvanic cell relies on the exchange of electrons between two cells due to a redox reaction. This means that it must consist of a cell that undergoes oxidation and loses electrons, which then travel to the cell undergoing reduction, causing a current. So unless you have a way of interchanging the two cells, the current will always travel in this direction.

YES, its possible.

You should know that in a v-cell , spontaneous redox reaction happens in which electric energy is produced from chemical energy.

You CAN change it into a reversible cell (electrolytic cell) by putting a source of electricity in the v-cell's circuit which opposes the voltaic cell i.e has greater voltage than the voltage produced by the v-cell. This external source of electricity u added tothe circuit will push the electrons in an opposite direction thus supplying energy tothe cell making it a non-spontaneous , reversed v-cell or simply a "electrolytic cell" in which electric energy is converted to chemical energy.