BFR FLT FM ANCHORAGE TO BETHEL, AK, NON-INST RATED PLT WAS ADZD THAT VFR FLT WASN'T RCMDD. EN ROUTE, HE CONVERSED WITH MCGRATH FSS WHILE VFR-ON-TOP & INDCD HE WOULD DSCND THRU HOLE IN CLDS TO LND/REFUEL AT LIME, AK. AT 1948 ADT, HE RPRTD EN ROUTE AGAIN, 150 MI EAST OF BETHEL. AT 2054, PLT CTCD BETHEL FSS FOR TFC & WX ADZY & RPRTD 40 MI EAST IN 'A LITTLE BIT OF FOG.' ABT 10 MIN LTR, HE SAID HE WAS GETTING DISORIENTED, REQD ASSISTANCE, THEN RPRTD '60 MI OUT.' HE INDCD HE COULDN'T SEE TO SET TRANSPONDER TO 7700 (AT NGT). AT 2106, HE RPRTD AT 6000' & ASKED ABT FCST CIG & 'HOW HI CAN I GO TO GET UP OUT OF THIS IF I GET SOME REFERENCE.' RDO CTC WAS LOST FOR ABT 12 MIN, THEN PLT SAID HE WAS AT 3700' & STILL 58 MI FM BETHEL. NO DF STROBE OR RADAR INFO WAS OBTAINED, THOUGH A DF STEER WAS BGN AT 2119, BUT WAS NOT ATTAINED. ACFT IMPACTED 45-50 DEG RISING TRRN ABT 100' BLO MTN RIDGE AT 3200' LVL. NO PREIMPACT PART FAILURE/MALFUNCTION WAS FND. EXAM REVEALED: ENG RPM 2699, THROTTLE/MIXTURE FULL FWD, AIRSPD 30 KTS. PROP WAS FND 15' UPHILL FM WRECKAGE WITH EXTSV DMG.