Too Long; Didn't Read
First of all: your wallet probably sucks, consider changing it. <br>Second: Don’t worry your coins are safe. <strong>Within three days your transaction either confirms or your coins “reappear” in your wallet.</strong> This is the short answer and it is probably correct about 99% of the times, but let’s dive deeper for in-depth understanding, then examine your options if you don’t want to just wait.<br><strong>Update: </strong>As <a href="https://www.reddit.com/r/Bitcoin/comments/69jywp/a_practical_guide_to_accidental_low_fee/dhjfthf/?utm_content=permalink&utm_medium=front&utm_source=reddit&utm_name=Bitcoin" target="_blank">/u/ismith23 noted</a>, from Bitcoin 0.14 “transaction reappearance” happens after 2 weeks.