Startup repair boot loop!

I get into startup repair everytime i boot my pc which is never successful. I am definitely goin to explain it in detail but dis is basic problem nd plz dont mind typing coz m typing fast on iphone which may cause errors in typing!!

Yesterday,i used my pc for 7-8 hrs continuosly which is not big deal but due to it i can't figure out my action which caused problem. I kept it on for downloading at night nd when in morning i got boot screen which comes when pc is directly turned off. I did Start Windows Normally nd i got usual windows 7 loading animation for a secong nd den it started startup repair after that everytime i boot it takes me to startup repair resulting in continuos failure. I hv googled nd found many threads but none matched my exact one. Startup infinity loop didn't work. Below r given few conclusions nd obstacles-
1.) i can't get into advanced boot options using F8. But i can get into recovery menu using install dvd nd view advanced options frm startup repair.
2.) System restore din't work. I mean its not successful in restoring.
3.) bootrec.exe didnt work
4.) imp point to be noted is my last update was on 23 dec while pc worked fine on 24 th & 25th dec means dont knw wat happened 25th night that caused this problem on 26th morning.
5.) sfc/scannow says "a startup repair is left to be completed." it says to complete that first then use sfc/scannow.
6.) chkdsk results in last line saying failed to transfer log......
7.) i also get a report like many others about that problem signature.
8.) repair install not possible coz windows can't start only.
9.)i hv made a backup using cmd but is there any way without clean install?

are you able to enter safe mode?