Discreet lack discovered after 4 years. Chances ?

Hello together, briefly to the situation: 4 years ago I bought a car from someone privately (declared as accident-free), since I will start a study next month the BAföG Office demanded the appointment of an expert, who should determine the value for my car. Here the expert found that the whole front and left side was repainted! Visually not to recognize as lay. Here a previous accident damage is probably very likely. can I there n Ach 4 years still do something at all, let alone prove. Thank you very much for your help.