AURORA, Colo. — Micaela Samol Gonzalez, dressed in blue detention scrubs, made her way to the front of a windowless courtroom in Colorado on Thursday and faced the judge. After she gave her name and arranged a future court date for her immigration case, the judge asked whether she had any questions.

She had just one.

“My question is regarding my son,” Ms. Gonzalez, whose boy was taken away by immigration authorities shortly after she was accused of crossing the border illegally on a journey from Guatemala, said in Spanish. “I’ve been given a number to contact him but nobody’s replying to me, and I’m wondering if he’s doing well.”

A day after President Trump signed an executive order scrapping his administration’s practice of separating immigrant parents and children at the border, there was no relief for Ms. Gonzalez and hundreds of other parents who were little closer to reuniting with the more than 2,300 children who have been taken from them under the administration’s “zero tolerance” border enforcement policy.

Parents said they still did not know how to track down their children, and struggled to find out any information through a 1-800 hotline set up by the federal Office of Refugee Resettlement. Others who had located their children said they were still separated by thousands of miles and a bureaucratic maze they did not know how to navigate.