Is the inability to trust anyone a psychiatric disorder?

Trust: Yes. For a healthy adaptation to life with a family, in a community, and at work it is necessary to have a basic amount of trust, or you will never end up getting close to anyone. Many people have been burned repeatedly by individuals who did not deserve their trust. Not trusting anyone is a maladaptive response that won't really help. Counseling can help you decide who deserves your trust.

Maybe: There is something called: paranoid personality disorder, although, I have no real way of knowing if that is your problem or whether you have another condition. The ability to trust others can be influenced by a variety of factors. There may be problems stemming from, for example, being abused as a child; there are other situations which contribute to feeling others can't be trusted. Good luck.