$re = '/^(?!NOT FOUND \*\*\*\*\* ).*$/m';
$str = 'a68ebf048cb21948ae814f88f8573267 *Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part23.rar
143bc5637fca8831800682da24fabdbe *Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part24.rar
eecbe9a184700963a09a3dc6486d1f72 *Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part25.rar
51f6341b48d44788775ee676e9fd106a *Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e03.Bastille.Day.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.sfv
NOT FOUND ***** Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part01.rar
NOT FOUND ***** Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part02.rar
NOT FOUND ***** Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part03.rar
NOT FOUND ***** Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part04.rar
NOT FOUND ***** Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part05.rar
NOT FOUND ***** Torrented Movies\\Battlestar Galactica\\Season 1\\Video Files\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL\\Battlestar.Galactica.s01e04.Act.Of.Contrition.iNTERNAL.WS.DVDRip.XviD-MEDiEVAL.part06.rar
';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php