First of all, to make one version of SRO not overload another at install - change the folder name of the existing SRO. Example: you have iSRO installed as: "Silkroad" folder. Change it to "iSilkroad" and then install cSRO as "Silkroad". Change the cSRO to "cSilkroad" and you can install another version. So on..

For the game not working. You probably downloaded the wrong client. Here's the right one:
http://files.filefront.com/SilkroadOnli ... einfo.htmlTo change your iSRO back to English: delete everything in the folder and reinstall. Your media.pk2's were probably mixed up or something. If you followed some guides to do something to change cSRO, undo
