During re-entry, also on autopilot, there was no communication between her ship and the ground, and she ended up landing in an unexpected place. She said there had been a communications equipment failure, but the team on the ground blamed her for going silent.
Tereshkova's role in the flight's problems may never be completely known. The Soviets certainly had engineering challenges with their rockets, including one which led to the only three deaths in space. (Both the Challenger and Columbia disasters happened inside Earth's atmosphere, thus not technically "in space.")
Memoirs from other members of the Soviet space team have blamed Tereshkova for her problematic mission, but the idea that she was forced against her will seems unlikely to be true. If the avid skydiver had changed her mind at the last minute, she could easily have stepped aside in favor of one of the other four female cosmonauts who had shared her 7 months of rigorous training.
In fact, the Soviets originally planned to launch two women in overlapping flights: Tereshkova first, in Vostok 5, and then Valentina Ponomaryova a few days later in Vostok 6. Though the Soviets did succeed in having two cosmonauts in space at the same time, the final plan included Tereshkova in Vostok 6 following Valery Bykovsky, who had launched two days earlier.
When Tereshkova's solo ship passed close to Mr. Bykovsky's Vostok 5, they chatted and even sang songs together, until their ships got too far apart for communication.
Tereshkova was probably selected to fly because of her experience with weightlessness: prior to joining the cosmonaut program, she had completed dozens of successful parachute jumps. Not only did that give her experience with the sensation of freefall, which she experienced throughout her three days in space, but the Soviet rockets completed re-entry with the cosmonauts bailing out of the re-entry vessel and parachuting onto the ground, making her experience doubly helpful. Her cosmonaut training included another 120 parachute jumps.