i have had this problem in the past so i will try to help. i am guessing you use the trainer in this link here http://www.gta4-mods.com/script/simple-trainer-version-65-f2115
just go step by step with your installation. once you reinstall GTA IV with the patch from Rockstar provided here: https://support.rockstargames.com/hc/en-us/articles/200145406-Grand-Theft-Auto-IV-Patch-7-Title-Update-v-1-0-7-0-English-1-0-6-1-Russian-1-0-5-2-Japanese-
once you have the game installed check it out to make sure it runs good. then install LCPDFR automatically. make sure you disable your virus protection while you are downloading and installing LCPDFR as some programs will block certain components from being installed. You should whitelist any part of LCPDFR so it wont be a problem later on :)
after you confirm that your LCPDFR is working then install your native trainer. the only things in the trainer folder you need to install are trainer.ini and trainer.asi. do not install the scripthook files that come with the trainer. they are outdated and the ones that come with LCPDFR are new. now that is the exact way i re installed mine because i had the same issue. so let's hope it works.
in the meantime, dont install ELS or anything else until we figure out what is going on here okay :) let me know if any of this helped your situation