Just to share with you guys, just now while i was playing AC4 on my PS4. I ejected the disc using the options menu after finishing playing. The disc came out but then the PS4 would not accept any disc into it. It was also was making some ' wish ~~' sound from the disc reader section. I restarter the PS4 and the problem still occures After doing some googling, i tried adjusting the disc manual ejection screw in the PS4 and solve it   Refer this link HERE. Hope this help those who encounter the same problem as i have.