MySQL: Can't find record in tablename
You can try to use the REPAIR TABLE myTable USE_FRM

"Probably" your .MYI file is missing or have corrupted headers


  This option tells MySQL not to trust the information in the .MYI file
  header and to re-create it using information from the .frm file


However before proceed check the documentation of your MySQL 5.1 version and make a backup copy of your .MYI,.frm, and .MYD file in order to avoid loss of data